Choose the proper verb in the box and fill in the blanks.

is spent  did... arrive  does   is smoking  have been waiting

--How do you spend your money?

Choose the proper verb in the box and fill in the blanks.

is spent  did... arrive  does   is smoking  have been waiting

--When _________ you ________?

Choose the proper verb in the box and fill in the blanks.

is spent  did... arrive  does   is smoking  have been waiting

He says he'll stop smoking, but he never __________. When I see him, he ________.

Choose the proper words and fill in the blanks.

We are destroying our best fighters against __________ (pollute/pollution).

Choose the proper words and fill in the blanks.

The trees can produce a _________ (chemical/chemistry) to protect themselves.

Choose the proper words and fill in the blanks.

They take harmful gas from the air, and _______ (receive/release) oxygen into the air.

Choose the proper words and fill in the blanks.

I _______ (suggest/suppose) you also enjoy breathing pure, cool air.

Choose the proper words and fill in the blanks.

Trees are the biggest and oldest __________ (living/alive) things on the earth.

Choose the proper verb in the box and fill in the blanks.

come    not see    give    receive　　  should clean

Yesterday I _________ a letter from Jack. He is my good friend. 

We _________ each other for two years. In the letter he told me that he _______ to visit me soon.

Choose the proper verb in the box and fill in the blanks.

come　　 not see　　  give　　   receive　　   should clean

--The classroom is dirty. It _________.

--All right. We ______ our classroom a good cleaning.