【简答题】前照灯有哪些元件构成?前照灯特性由哪些?
【单选题】设有Teachers表,该表的定义如下:CREATE TABLE Teachers( Tno CHAR(8) PRIMARY KEY, Tname VARCHAR(10) NOT NULL, Age TINYINT CHECK(Age BETWEEN 25 AND 65) )插入语句中,不能正确执行的是( )。
A.
INSERT INTO Teachers VALUES('T100','张宏',NULL)
B.
INSERT INTO Teachers(Tno,Tname,Age) VALUES('T100','张宏',30)
C.
INSERT INTO Teachers(Tno,Tname) VALUES('T100','张宏')
D.
INSERT INTO Teachers VALUES('T100','张宏')
【单选题】设有Teachers表,该表的定义如下: CREATE TABLE Teachers( Tno CHAR(8) PRIMARY KEY, Tname VARCHAR(10) NOT NULL, Age TINYINT CHECK(Age BETWEEN 25 AND 65) ) 下列插入语句中,不能正确执行的是( )。
A.
INSERT INTO Teachers VALUES('T100','张鸿',NULL)
B.
INSERT INTO Teachers(Tno,Tname,Age) VALUES('T100','张鸿',30)
C.
INSERT INTO Teachers(Tno,Tname) VALUES('T100','张鸿')
D.
INSERT INTO TeachersVALUES('T100','张鸿')
【单选题】设有Teachers表,该表的定义如下: CREATE TABLE Teachers( Tno CHAR(8) PRIMARY KEY, Tname VARCHAR(10) NOT NULL, Age TINYINT CHECK(Age BETWEEN 25 AND 65) ) 下列插入语句中,不能正确执行的是
A.
INSERT INTO Teachers VALUES('T100',' 张三 ',NULL)
B.
INSERT INTO Teachers(Tno,Tname,Age) VALUES('T100',' 张三 ',30)
C.
INSERT INTO Teachers(Tno,Tname) VALUES('T100',' 张三 ')
D.
INSERT INTO TeachersVALUES('T100',' 张三 ')
【单选题】在制备电子显微镜观察组织样本时常用的固定试剂是
【单选题】若软弱下卧层承载力不能满足要求,下列哪个措施是无效的?
【单选题】若软弱下卧层承载力不能满足要求,下列( )措施是无效的。