diff --git a/1. Python 安装及基本语法.ipynb b/1. Python 安装及基本语法.ipynb
index da1185c..72e4da8 100644
--- a/1. Python 安装及基本语法.ipynb	
+++ b/1. Python 安装及基本语法.ipynb	
@@ -197,64 +197,31 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 6,
+   "execution_count": null,
    "source": [
     "## 2 表示 整数(integer) 2\n",
     "type(2)"
    ],
-   "outputs": [
-    {
-     "output_type": "execute_result",
-     "data": {
-      "text/plain": [
-       "int"
-      ]
-     },
-     "metadata": {},
-     "execution_count": 6
-    }
-   ],
+   "outputs": [],
    "metadata": {}
   },
   {
    "cell_type": "code",
-   "execution_count": 7,
+   "execution_count": null,
    "source": [
     "## 2.333 与 1e-9 表示对应浮点数(float)\n",
     "type(2.33)"
    ],
-   "outputs": [
-    {
-     "output_type": "execute_result",
-     "data": {
-      "text/plain": [
-       "float"
-      ]
-     },
-     "metadata": {},
-     "execution_count": 7
-    }
-   ],
+   "outputs": [],
    "metadata": {}
   },
   {
    "cell_type": "code",
-   "execution_count": 8,
+   "execution_count": null,
    "source": [
     "type(1e-9)"
    ],
-   "outputs": [
-    {
-     "output_type": "execute_result",
-     "data": {
-      "text/plain": [
-       "float"
-      ]
-     },
-     "metadata": {},
-     "execution_count": 8
-    }
-   ],
+   "outputs": [],
    "metadata": {}
   },
   {
@@ -281,7 +248,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 24,
+   "execution_count": 11,
    "source": [
     "## True 代表逻辑值(Boolen)\n",
     "type(True)"
@@ -295,7 +262,28 @@
       ]
      },
      "metadata": {},
-     "execution_count": 24
+     "execution_count": 11
+    }
+   ],
+   "metadata": {}
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 12,
+   "source": [
+    "\n",
+    "type(False)"
+   ],
+   "outputs": [
+    {
+     "output_type": "execute_result",
+     "data": {
+      "text/plain": [
+       "bool"
+      ]
+     },
+     "metadata": {},
+     "execution_count": 12
     }
    ],
    "metadata": {}
@@ -312,13 +300,13 @@
    "source": [
     "与常量相反，变量可以存储不同的值以表示不同的内容，并且它的值可以被更改。变量通过赋值符号 = 创建，例如variable = 1。\n",
     "\n",
-    "注意变量存在命名规范。变量的第一个字符必须是字母，其余部分由下划线或数字组成，且区分大小写。例如 a_123 可以是一个变量，123_a 不可以是一个变量，A_123 与 a_123 表示两个不同变量。"
+    "注意变量存在命名规范。变量的第一个字符必须是字母或下划线，其余部分由下划线或数字组成，且区分大小写。例如 a_123 可以是一个变量，123_a 不可以是一个变量，A_123 与 a_123 表示两个不同变量。"
    ],
    "metadata": {}
   },
   {
    "cell_type": "code",
-   "execution_count": 14,
+   "execution_count": 13,
    "source": [
     "## 创建名为 variable 的变量存储一个 整数 值\n",
     "\n",
@@ -334,7 +322,7 @@
       ]
      },
      "metadata": {},
-     "execution_count": 14
+     "execution_count": 13
     }
    ],
    "metadata": {}
@@ -364,7 +352,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 19,
+   "execution_count": 16,
    "source": [
     "## 常量的值无法修改 触发语法错误提示\n",
     "\n",
@@ -374,9 +362,9 @@
     {
      "output_type": "error",
      "ename": "SyntaxError",
-     "evalue": "cannot assign to literal (<ipython-input-19-11df37b38908>, line 3)",
+     "evalue": "cannot assign to literal (<ipython-input-16-11df37b38908>, line 3)",
      "traceback": [
-      "\u001b[0;36m  File \u001b[0;32m\"<ipython-input-19-11df37b38908>\"\u001b[0;36m, line \u001b[0;32m3\u001b[0m\n\u001b[0;31m    2.33 = 2.55\u001b[0m\n\u001b[0m    ^\u001b[0m\n\u001b[0;31mSyntaxError\u001b[0m\u001b[0;31m:\u001b[0m cannot assign to literal\n"
+      "\u001b[0;36m  File \u001b[0;32m\"<ipython-input-16-11df37b38908>\"\u001b[0;36m, line \u001b[0;32m3\u001b[0m\n\u001b[0;31m    2.33 = 2.55\u001b[0m\n\u001b[0m    ^\u001b[0m\n\u001b[0;31mSyntaxError\u001b[0m\u001b[0;31m:\u001b[0m cannot assign to literal\n"
      ]
     }
    ],
@@ -384,7 +372,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 20,
+   "execution_count": 17,
    "source": [
     "## 变量的命名不满足规范 触发语法错误提示\n",
     "\n",
@@ -394,9 +382,9 @@
     {
      "output_type": "error",
      "ename": "SyntaxError",
-     "evalue": "invalid decimal literal (<ipython-input-20-594a879f97d7>, line 3)",
+     "evalue": "invalid decimal literal (<ipython-input-17-bb1ef621bcb6>, line 3)",
      "traceback": [
-      "\u001b[0;36m  File \u001b[0;32m\"<ipython-input-20-594a879f97d7>\"\u001b[0;36m, line \u001b[0;32m3\u001b[0m\n\u001b[0;31m    123_a = 1\u001b[0m\n\u001b[0m       ^\u001b[0m\n\u001b[0;31mSyntaxError\u001b[0m\u001b[0;31m:\u001b[0m invalid decimal literal\n"
+      "\u001b[0;36m  File \u001b[0;32m\"<ipython-input-17-bb1ef621bcb6>\"\u001b[0;36m, line \u001b[0;32m3\u001b[0m\n\u001b[0;31m    123_a = 1\u001b[0m\n\u001b[0m       ^\u001b[0m\n\u001b[0;31mSyntaxError\u001b[0m\u001b[0;31m:\u001b[0m invalid decimal literal\n"
      ]
     }
    ],
@@ -473,14 +461,14 @@
     "例如：\n",
     "\n",
     "    输入：2,3,7,11,15, target = 13\n",
-    "    输出：2,7\n",
-    "    解释：第0个数和第2个数的和为13 （注：编程时我们习惯从第0个开始数）"
+    "    输出：2,11\n",
+    "    解释：第0个数和第3个数的和为13 （注：编程时我们习惯从第0个开始数）"
    ],
    "metadata": {}
   },
   {
    "cell_type": "code",
-   "execution_count": 36,
+   "execution_count": 29,
    "source": [
     "## 尝试求解，改变 a b 的值依次两两尝试，直到 a + b = target\n",
     "\n",
@@ -498,14 +486,14 @@
       ]
      },
      "metadata": {},
-     "execution_count": 36
+     "execution_count": 29
     }
    ],
    "metadata": {}
   },
   {
    "cell_type": "code",
-   "execution_count": 37,
+   "execution_count": 30,
    "source": [
     "a = 2\n",
     "b = 7\n",
@@ -520,14 +508,14 @@
       ]
      },
      "metadata": {},
-     "execution_count": 37
+     "execution_count": 30
     }
    ],
    "metadata": {}
   },
   {
    "cell_type": "code",
-   "execution_count": 38,
+   "execution_count": 31,
    "source": [
     "a = 2\n",
     "b = 11\n",
@@ -542,14 +530,14 @@
       ]
      },
      "metadata": {},
-     "execution_count": 38
+     "execution_count": 31
     }
    ],
    "metadata": {}
   },
   {
    "cell_type": "code",
-   "execution_count": 39,
+   "execution_count": 32,
    "source": [
     "a,b"
    ],
@@ -562,7 +550,7 @@
       ]
      },
      "metadata": {},
-     "execution_count": 39
+     "execution_count": 32
     }
    ],
    "metadata": {}
@@ -601,7 +589,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 62,
+   "execution_count": 33,
    "source": [
     "## 自动输出最后的 target\n",
     "\n",
@@ -617,14 +605,14 @@
       ]
      },
      "metadata": {},
-     "execution_count": 62
+     "execution_count": 33
     }
    ],
    "metadata": {}
   },
   {
    "cell_type": "code",
-   "execution_count": 63,
+   "execution_count": 34,
    "source": [
     "## 自动输出最后的 variable\n",
     "\n",
@@ -640,7 +628,7 @@
       ]
      },
      "metadata": {},
-     "execution_count": 63
+     "execution_count": 34
     }
    ],
    "metadata": {}
@@ -654,7 +642,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 65,
+   "execution_count": 36,
    "source": [
     "## num1，num2 是输入的参数， return 后面的 a+b==target 是函数的结果\n",
     "\n",
@@ -686,7 +674,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 66,
+   "execution_count": 37,
    "source": [
     "## 这里 2,3,13 是实参，函数返回结果 False\n",
     "\n",
@@ -725,11 +713,11 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 67,
+   "execution_count": 38,
    "source": [
     "## 尝试在函数外部使用变量 num1，系统报错 num1 未定义\n",
     "\n",
-    "num1"
+    "print(num1)"
    ],
    "outputs": [
     {
@@ -739,7 +727,7 @@
      "traceback": [
       "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
       "\u001b[0;31mNameError\u001b[0m                                 Traceback (most recent call last)",
-      "\u001b[0;32m<ipython-input-67-480f0d231548>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m\u001b[0m\n\u001b[1;32m      1\u001b[0m \u001b[0;31m## 尝试在函数外部使用变量 num1，系统报错 num1 未定义\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m      2\u001b[0m \u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m----> 3\u001b[0;31m \u001b[0mnum1\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
+      "\u001b[0;32m<ipython-input-38-9b7c7bff9b5d>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m\u001b[0m\n\u001b[1;32m      1\u001b[0m \u001b[0;31m## 尝试在函数外部使用变量 num1，系统报错 num1 未定义\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m      2\u001b[0m \u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m----> 3\u001b[0;31m \u001b[0mprint\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mnum1\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
       "\u001b[0;31mNameError\u001b[0m: name 'num1' is not defined"
      ]
     }
@@ -748,7 +736,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 68,
+   "execution_count": 39,
    "source": [
     "## 尝试重新定义函数 check_sum, 此时函数参数中已不存在target\n",
     "\n",
@@ -763,7 +751,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 71,
+   "execution_count": 40,
    "source": [
     "print(check_sum(2, 3))\n",
     "\n",
@@ -801,7 +789,7 @@
   {
    "cell_type": "markdown",
    "source": [
-    "通过控制符与函数，我们可以操作变量完成简单的任务。然而本质上我们还在把 Python 当作一个计算器使用，而不是一个可以实现自动化的编程语言，每行代码按照自上而下的顺序依次执行。通过控制流，我们可以让程序自动判断逻辑，自动跳转到某个位置，从而实现自动控制。\n",
+    "通过运算符与函数，我们可以操作变量完成简单的任务。然而本质上我们还在把 Python 当作一个计算器使用，而不是一个可以实现自动化的编程语言，每行代码按照自上而下的顺序依次执行。通过控制流，我们可以让程序自动判断逻辑，自动跳转到某个位置，从而实现自动控制。\n",
     "\n",
     "控制流中涉及几个关键字：\n",
     "\n",
@@ -831,7 +819,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 76,
+   "execution_count": 41,
    "source": [
     "## while 循环语句样例\n",
     "\n",
@@ -886,7 +874,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 77,
+   "execution_count": 42,
    "source": [
     "## for-in 循环语句样例\n",
     "\n",
@@ -917,7 +905,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 81,
+   "execution_count": 43,
    "source": [
     "## 依次迭代元素 a，一共迭代 5 次\n",
     "for a in [2,3,7,11,15]:\n",
@@ -986,6 +974,13 @@
    ],
    "metadata": {}
   },
+  {
+   "cell_type": "markdown",
+   "source": [
+    "> 女朋友说，下班回来带一个西瓜。如果看到番茄，就买两个。最后程序员买回来两个西瓜。"
+   ],
+   "metadata": {}
+  },
   {
    "cell_type": "markdown",
    "source": [
@@ -997,7 +992,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 85,
+   "execution_count": 44,
    "source": [
     "## 加入 if-else 逻辑语句\n",
     "\n",
@@ -1046,7 +1041,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 87,
+   "execution_count": 45,
    "source": [
     "## 添加 break 停止语句\n",
     "\n",
@@ -1092,7 +1087,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 89,
+   "execution_count": 46,
    "source": [
     "for a in [2,3,7,11,15]:\n",
     "    print(a)\n",
@@ -1150,7 +1145,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 108,
+   "execution_count": null,
    "source": [
     "## 定义阶乘函数，用于排列组合中\n",
     "def multiple(x):\n",
@@ -1165,7 +1160,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 110,
+   "execution_count": null,
    "source": [
     "## 定义二项分布计算函数\n",
     "def p_xk(k):\n",
@@ -1181,7 +1176,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 117,
+   "execution_count": null,
    "source": [
     "## 根据二项分布计算概率\n",
     "k = 0\n",
@@ -1189,35 +1184,7 @@
     "    print('P{ X =',k,'} = ', p_xk(k))\n",
     "    k = k + 1"
    ],
-   "outputs": [
-    {
-     "output_type": "stream",
-     "name": "stdout",
-     "text": [
-      "P{ X = 0 } =  0.011529215046068483\n",
-      "P{ X = 1 } =  0.05764607523034242\n",
-      "P{ X = 2 } =  0.13690942867206327\n",
-      "P{ X = 3 } =  0.20536414300809488\n",
-      "P{ X = 4 } =  0.21819940194610074\n",
-      "P{ X = 5 } =  0.17455952155688062\n",
-      "P{ X = 6 } =  0.10909970097305038\n",
-      "P{ X = 7 } =  0.054549850486525185\n",
-      "P{ X = 8 } =  0.022160876760150862\n",
-      "P{ X = 9 } =  0.007386958920050286\n",
-      "P{ X = 10 } =  0.0020314137030138287\n",
-      "P{ X = 11 } =  0.00046168493250314287\n",
-      "P{ X = 12 } =  8.65659248443393e-05\n",
-      "P{ X = 13 } =  1.3317834591436813e-05\n",
-      "P{ X = 14 } =  1.6647293239296018e-06\n",
-      "P{ X = 15 } =  1.6647293239296019e-07\n",
-      "P{ X = 16 } =  1.3005697843200012e-08\n",
-      "P{ X = 17 } =  7.65041049600001e-10\n",
-      "P{ X = 18 } =  3.1876710400000044e-11\n",
-      "P{ X = 19 } =  8.38860800000001e-13\n",
-      "P{ X = 20 } =  1.0485760000000012e-14\n"
-     ]
-    }
-   ],
+   "outputs": [],
    "metadata": {}
   }
  ],