________ the pollution, not enough heat is leaving the earth．

A．For

B．Because

C．Since

D．Because of

This math problem is ________ that one．

A．so easy as

B．as difficult as

C．much difficult than

D．less easier than

Zhang Daming swims quite well in the river, just ________ a fish．

A．for

B．like

C．with

D．seem

My mother often asks my father ________ too much wine．It's bad for his health．

A．doesn't drink

B．not to drink

C．not drink

D．not drinking

We should change our bad habit of using plastic bags, and then we can ________ our earth．

A．damage

B．destroy

C．threat

D．protect

Many people like to plant trees around their houses because trees can ________ CO₂．

A．turn into

B．release into

C．burn up

D．take in

Your books are everywhere．Please ________．

A．put away it

B．put it away

C．put away them

D．put them away

The bag ________ 50 yuan last week, but now it ________ only 30 yuan．

A．cost; costs

B．cost; takes

C．takes; take

D．took; cost

The police make the city a safe place to live and ________．

A．work

B．work in

C．working

D．working in

________ of the land ________ covered with trees．

A．One third; was

B．Two third; is

C．One half; are

D．A quarter; were