1 . —Earth is ________ only home to everyone.
—Let’s try to make it ________ greener world to live in.

A．a; a

B．a; the

C．the; a

2 . The Grand Canyon is ________ great wonder of ________ natural world.

A．an; the

B．the; a

C．the; 不填

D．a; the

3 . —Do you know anything about ________ Earth?     
—Yes. It provides water and food ________ us.

A．a; for

B．an; with

C．the; for

D．/; with

4 . London is in the south of England and it is on ________ River Thames.

A．a

B．the

C．an

D．/

5 . They are having ________ great time under ________ sun.

A．a; an

B．an; a

C．an; the

D．a; the

6 . —Fishermen are not allowed to fish in ________ Changjiang River.
—Yes, we all want to create ________ more beautiful world.

A．a; a

B．the; the

C．the; a

D．a; the

7 . If we want to go on living on ________ earth, we should care about ________ environment.

A．/; /

B．the; /

C．the; the

D．an; an

8 . _____ sun is shining.

A．The

B．A

C．An

9 . —Do you use ________ Internet to study?
—Yes, I use it once ________ week.

A．the; the

B．the; /

C．the; a

D．a; a

10 . _________ Earth is bigger than _________ Moon.

A．A, a

B．An, a

C．The, the

D．/, /