diff --git a/tests/system-test/2-query/timezone.py b/tests/system-test/2-query/timezone.py
index a3bc3b5d6b..a93ecc90c4 100644
--- a/tests/system-test/2-query/timezone.py
+++ b/tests/system-test/2-query/timezone.py
@@ -41,6 +41,7 @@ class TDTestCase:
         tdSql.query("select * from normaltb where ts=today()")
         tdSql.checkRows(1)
         tdSql.checkData(0,1,3)
+        # for bug TD-14905
         # for i in range(0,50):
         #     tdSql.query("select timezone() from db.normaltb")
         #     tdSql.checkData(0,0,"Asia/Shanghai (CST, +0800)")
@@ -140,118 +141,146 @@ class TDTestCase:
         tdSql.query("select timezone() from normaltb where ts=today()")
         tdSql.checkRows(1)
 
+        tdSql.query("select timezone() from normaltb where ts<now()")
+        tdSql.checkRows(3)
+        tdSql.query("select timezone() from normaltb where ts<=now()")
+        tdSql.checkRows(3)
+
+        # for bug TD-14918
         # tdSql.query("select timezone() from normaltb where ts=now()")
         # tdSql.checkRows(0)
+        # tdSql.query("select timezone() from normaltb where ts >now()")
+        # tdSql.checkRows(0)
+        # tdSql.query("select timezone() from normaltb where ts >=now()")
+        # tdSql.checkRows(0)
 
 
 
-        # tdLog.printNoPrefix("==========step3:create super table==========")
-        # tdSql.execute("create table stb (ts timestamp,c0 int) tags(t0 int)")
-        # tdSql.execute("create table stb_1 using stb tags(1)")
-        # tdSql.execute("create table stb_2 using stb tags(2)")
+        tdLog.printNoPrefix("==========step3:create super table==========")
+        tdSql.execute("create table stb (ts timestamp,c0 int) tags(t0 int)")
+        tdSql.execute("create table stb_1 using stb tags(1)")
+        # tdSql.execute("create table stb_2 using stb tags(1)")
 
-        # tdLog.printNoPrefix("==========step4:insert data==========")
-        # tdSql.execute("insert into stb_1 values(now(),1000)")
-        # tdSql.query("select timezone() from stb")
-        # tdSql.checkRows(1)
+        tdLog.printNoPrefix("==========step4:insert data==========")
+        tdSql.execute("insert into stb_1 values(now(),1000)")
+        tdSql.query("select timezone() from stb")
+        tdSql.checkRows(1)
         # tdSql.checkData(0,0,"Asia/Shanghai (CST, +0800)")
 
-        # tdSql.execute("insert into stb_1 values(now(),1000)")
+        tdSql.query("select timezone() from stb where ts<=now()")
+        tdSql.checkRows(1)
+        tdSql.query("select timezone() from stb where ts<now()")
+        tdSql.checkRows(1)
+        
+        # for bug TD-14918
+        # tdSql.query("select timezone() from stb where ts=now()")
+        # tdSql.checkRows(0)
+        # tdSql.query("select timezone() from stb where ts>=now()")
+        # tdSql.checkRows(0)
+        # tdSql.query("select timezone() from stb where ts>now()")
+        # tdSql.checkRows(0)
+
+        tdSql.execute("insert into stb_1 values(now(),1000)")
         # tdSql.query("select timezone() from stb")
-        # tdSql.checkRows(1)
+        # tdSql.checkRows(2)
         # tdSql.checkData(0,0,"Asia/Shanghai (CST, +0800)")
 
         # tdSql.execute("insert into stb_2 values(now,1000)")
         # tdSql.query("select timezone() from stb")
-        # tdSql.checkRows(2)
-
-        # tdSql.query("select now() from stb")
         # tdSql.checkRows(3)
 
-        # tdSql.query("select now() +1w from db.stb")
-        # tdSql.checkRows(3)
-        # tdSql.query("select now() +1w from stb")
-        # tdSql.checkRows(3) 
+        tdSql.query("select now() from stb")
+        tdSql.checkRows(3)
 
-        # tdSql.query("select now() +1d from db.stb")
-        # tdSql.checkRows(3)
-        # tdSql.query("select now() +1d from stb")
-        # tdSql.checkRows(3) 
+        tdSql.query("select now() +1w from db.stb")
+        tdSql.checkRows(3)
+        tdSql.query("select now() +1w from stb")
+        tdSql.checkRows(3) 
 
-        # tdSql.query("select now() +1h from db.stb")
-        # tdSql.checkRows(3)
-        # tdSql.query("select now() +1h from stb")
-        # tdSql.checkRows(3)
+        tdSql.query("select now() +1d from db.stb")
+        tdSql.checkRows(3)
+        tdSql.query("select now() +1d from stb")
+        tdSql.checkRows(3) 
 
-        # tdSql.query("select now() +1m from db.stb")
-        # tdSql.checkRows(3)
-        # tdSql.query("select now() +1m from stb")
-        # tdSql.checkRows(3)
+        tdSql.query("select now() +1h from db.stb")
+        tdSql.checkRows(3)
+        tdSql.query("select now() +1h from stb")
+        tdSql.checkRows(3)
 
-        # tdSql.query("select now() +1s from db.stb")
-        # tdSql.checkRows(3)
-        # tdSql.query("select now() +1s from stb")
-        # tdSql.checkRows(3)
+        tdSql.query("select now() +1m from db.stb")
+        tdSql.checkRows(3)
+        tdSql.query("select now() +1m from stb")
+        tdSql.checkRows(3)
 
-        # tdSql.query("select now() +1a from db.stb")
-        # tdSql.checkRows(3)
-        # tdSql.query("select now() +1a from stb")
-        # tdSql.checkRows(3)
+        tdSql.query("select now() +1s from db.stb")
+        tdSql.checkRows(3)
+        tdSql.query("select now() +1s from stb")
+        tdSql.checkRows(3)
 
-        # tdSql.query("select now() +1u from db.stb")
-        # tdSql.checkRows(3)
-        # tdSql.query("select now() +1u from stb")
-        # tdSql.checkRows(3)
+        tdSql.query("select now() +1a from db.stb")
+        tdSql.checkRows(3)
+        tdSql.query("select now() +1a from stb")
+        tdSql.checkRows(3)
 
-        # tdSql.query("select now() +1b from db.stb")
-        # tdSql.checkRows(3)
-        # tdSql.query("select now() +1b from stb")
-        # tdSql.checkRows(3)
+        tdSql.query("select now() +1u from db.stb")
+        tdSql.checkRows(3)
+        tdSql.query("select now() +1u from stb")
+        tdSql.checkRows(3)
 
-        # tdSql.query("select now() -1w from db.stb")
-        # tdSql.checkRows(3)
-        # tdSql.query("select now() -1w from stb")
-        # tdSql.checkRows(3)
+        tdSql.query("select now() +1b from db.stb")
+        tdSql.checkRows(3)
+        tdSql.query("select now() +1b from stb")
+        tdSql.checkRows(3)
 
-        # tdSql.query("select now() -1d from db.stb")
-        # tdSql.checkRows(3)
-        # tdSql.query("select now() -1d from stb")
-        # tdSql.checkRows(3)
+        tdSql.query("select now() -1w from db.stb")
+        tdSql.checkRows(3)
+        tdSql.query("select now() -1w from stb")
+        tdSql.checkRows(3)
 
-        # tdSql.query("select now() -1h from db.stb")
-        # tdSql.checkRows(3)
-        # tdSql.query("select now() -1h from sltb")
-        # tdSql.checkRows(3)
+        tdSql.query("select now() -1d from db.stb")
+        tdSql.checkRows(3)
+        tdSql.query("select now() -1d from stb")
+        tdSql.checkRows(3)
 
-        # tdSql.query("select now() -1m from db.stb")
-        # tdSql.checkRows(3)
-        # tdSql.query("select now() -1m from stb")
-        # tdSql.checkRows(3)
+        tdSql.query("select now() -1h from db.stb")
+        tdSql.checkRows(3)
+        tdSql.query("select now() -1h from stb")
+        tdSql.checkRows(3)
 
-        # tdSql.query("select now() -1s from db.stb")
-        # tdSql.checkRows(3)
-        # tdSql.query("select now() -1s from stb")
-        # tdSql.checkRows(3)
+        tdSql.query("select now() -1m from db.stb")
+        tdSql.checkRows(3)
+        tdSql.query("select now() -1m from stb")
+        tdSql.checkRows(3)
 
-        # tdSql.query("select now() -1a from db.stb")
-        # tdSql.checkRows(3)
-        # tdSql.query("select now() -1a from stb")
-        # tdSql.checkRows(3)
+        tdSql.query("select now() -1s from db.stb")
+        tdSql.checkRows(3)
+        tdSql.query("select now() -1s from stb")
+        tdSql.checkRows(3)
+
+        tdSql.query("select now() -1a from db.stb")
+        tdSql.checkRows(3)
+        tdSql.query("select now() -1a from stb")
+        tdSql.checkRows(3)
+
+        tdSql.query("select now() -1u from db.stb")
+        tdSql.checkRows(3)
+        tdSql.query("select now() -1u from stb")
+        tdSql.checkRows(3)
+
+        tdSql.query("select now() -1b from db.stb")
+        tdSql.checkRows(3)
+        tdSql.query("select now() -1b from stb")
+        tdSql.checkRows(3)
+
+        tdSql.execute("insert into stb_1 values(today(),100)")
+        tdSql.query("select * from stb_1 where ts=today()")
+        tdSql.checkRows(1)
+        tdSql.checkData(0,1,100)
+
+        # tdSql.execute()
 
-        # tdSql.query("select now() -1u from db.stb")
-        # tdSql.checkRows(3)
-        # tdSql.query("select now() -1u from stb")
-        # tdSql.checkRows(3)
 
-        # tdSql.query("select now() -1b from db.stb")
-        # tdSql.checkRows(3)
-        # tdSql.query("select now() -1b from stb")
-        # tdSql.checkRows(3)
 
-        # tdSql.execute("insert into stb_1 values(today(),100)")
-        # tdSql.query("select * from stb_1 where ts=today()")
-        # tdSql.checkRows(1)
-        # tdSql.checkData(0,0,100)
 
 
     def stop(self):