I don’t think the book is useful, ________?

A．don’t I

B．is it

C．doesn’t it

D．isn’t it

However, no one ________ any life in space yet．

A．has been discovered

B．discovered

C．has discovered

D．have discovered

It was said that some spacecraft have gone ________ the solar system．

A．into

B．beyond

C．out

D．towards

It is hard ________ his strange idea．

A．understand

B．say

C．understood

D．to understand

The Sun and its planets ________ the solar system．

A．called

B．named

C．is called

D．are called

Scientists think there has been life on Earth for ________ years．

A．millions of

B．hundreds of

C．five million of

D．million of

He has ever read the story book, ________　________?

A．doesn’t he

B．has he

C．hasn’t he

D．does he

－How many of you have been to the USA?

A．None

B．No one

C．Nobody

D．Somebody

I’ve found your watch．You ________ it on my desk yesterday．

A．left

B．have left

C．forgot

D．have forgotten

________ Mary has grown up, it doesn’t mean she can do what she likes．

A．Because

B．After

C．Although

D．But