I won’t tell the student the answer to the math problem until he ________ on it for more than an hour．

has been working

will have worked

will have been working

had worked

My friend, who ________ on the International Olympic Committee all his life, is retiring next month．

served

is serving

had served

has served

My parents have always made me ________ about myself, even I was twelve．

feeling well

feeling good

feel well

feel good

He has made a lot of films, but ________ are good ones．

any

some

few

many

There isn’t any milk in the fridge．________?

Was it all finished

Has it all finished

Has it all been finished

Did it all finish

So far, he must have achieved his goal, ________?

mustn’t he

didn’t he

hasn’t he

doesn’t he

Not until you try to build a machine that does the same task as people do ________．

you realize how is it incredibly hard

do you realize how incredibly hard it is

you realize how incredibly hard is it

do you realize how it is incredibly hard

After the whistle rang, the coach appeared in the field．Behind him ________ the team wearing black and white suits．

had

walked

was followed

led

Every day, ________, eighty Americans take their own lives from the work and life pressure．

on general

on average

on whole

at last

Joanna ________ her husband, who is enthusiastic about classical music．

believes

raises

supports

offers