车辆维护的原则是( )。 A．预防为主 B．定期维修 C．强制维修 D．维修为主

今年开学以来，我省中小学和幼儿园遵循教育部有关通知要求，积极创建“无烟校园”。 这主要体现了对未成年人的

A．家庭保护

B．学校保护

C．司法保护

D．社会保护

若函数y=|2^x-1|，在（-∞，m]上单调递减，则m的取值范围是______．

补全对话。

A: John, may I ask you some questions ?

B: OK . What is it ?

A: 1___________

B: I am from Canada

A: Really ? It's very far from here . so 2____________

B: I speak English and a little French. And I can also speak a little Chinese now.

A: How great you are ! 3_____________

B: I want to be an actor like my father .

A: Your father is an actor ! Very exciting!

B: Do you want to watch my father's movie in my home this afternoon?

A: Yes, of course. 4______________

B: It's across from the post office, you can find my house easily.

A: OK! 5_______________

B: See you this afternoon!

降尘装置不能正常使用时，（）作业。

A.可以

B.禁止

C.减缓割煤速度

D.加快割煤速度

夷夏之间，最大的不同乃在于（）。

A.血缘

B.种族

C.文明

D.地域