【单选题】下列物质中,不能用NaOH标准溶液直接准确滴定的是()。
【单选题】下列物质中,不能用 NaOH 标准溶液直接准确滴定的是( ) ( 已知 H 2 CO 3 : p K a1 = 6.38 , p K a2 = 10.25 ;邻苯二甲酸: p K a1 = 2.95 , p K a2 = 5.41 ;六亚甲基四胺: p K b = 8.85 )
【单选题】下面SQL正确的是?
A.
SELECT * FROM Tb_Stu_Score WHERE score>=80
B.
SELECT * FROM Tb_Stu_Score WHERE score BETWEEN 70 AND 80
C.
SELECT * FROM Tb_Stu_Info WHERE Stu_Address in ('湖北荆州','浙江温州')
D.
SELECT * FROM Tb_Stu_Info WHERE Stu_Address = '湖南%'
【判断题】因曲轴主轴瓦圆孔是一体加工的,为保证孔的圆度,和形位公差,如生产记号不清晰,则需自己按顺序做记号。
【单选题】下面 SQL 语句不正确的是
B.
update user set username=’zhangsan’ where id=’2’
D.
insert into user values(1,’zhang’,’pass’);
【单选题】下面SQL语句不正确的是
B.
update user set usernamezhangsan' where id2'
D.
insert into user values( lzhang ,'pass')