“开元盛世”与“贞观之治”的不同点是(   )

如图，D是△ABC的边AB上一点，在条件（1）∠ACD=∠B，（2）AC²=AD•AB，（3）AB边上与点C距离相等的点D有两个，（4）∠B=∠ACB中，一定使△ABC∽△ACD的个数是（　　）

选择恰当的句子补全下面的对话。

A: Hi, Jim. ____

B: I get up at 6:30. ____

A: Usually at 6:00. ____

B: I often wash my clothes and clean the windows.

A: Wow! ____

B: Do you do housework (家务活), too?

A: Yes, sometimes. ____

B: Sounds interesting!

A. You're so hard-working.

B. When do you get up on Saturdays?

C. What do you do on the weekend?

D. But I often play computer games.

E. What about you?

下列行为都是人们为了解决某些环境问题采取的措施，哪一项措施最容易导致相反的效果（　　）