1.    We often _________  our friends' homes without _______  them first.

A. drop by; call            B. drop by; calling

C. visit; call             D. visits; calling

5.    I see two big__________ (blackboard) on the wall.

4.    Who________ (knock) at my door? I was sleeping at that time.

3.    There are four___________ (season) in a year.

2.    It's good _________ (manner) to keep your voice down in public.

1.    We will build another new Great Green Wall across the__________ (north) part of China.

我的妹妹不该为那件事而生气。

My sister was not___________ _________ be angry about that. 

①Parents are __________ ( suppose) to teach their children how to behave well.

Now John is worth __________(talk) to.

Ladies and gentlemen, please fasten your seat belts. The plane is___________ . 

A. takes off     B. taking off

C. taking up    D. taking down