加封章只限于加封破损秘密载体时使用，起到（）的作用。A、区分处理日期 B、表示何局何

解不等式时，由3x＞-9，不等式两边______得x______；由-3x＜9，不等式两边______得x______．

They only stood there with their arms ______ in front of their chest rather than give us a hand.

A．folding

B．folded

C．to be folded

D．being folded

面对日益严重的水危机，作为一名中学生，应该做到也可以做到的是[ ]

A．不用水

B．防治水污染

C．节约用水

D．发展节水农业

A good teacher should leave some time for the students to ________ the knowledge. [ ]

A. introduce  

B. receive

C. digest  

D. accept