It is said in the book that Thomas Edison(1847-1931)________ the world leading inventor for sixty years．

would be

has been

had been

was

Although medical science ________ control over several dangerous diseases, what worries us is that some of them are returning．

achieve

has achieved

will achieve

had achieved

I ________ along the street looking for a place to park when the accident ________．

went; was occurring

went; occurred

was going; occurred

was going; had occurred

They ________ on the program for almost one week before I joined them, and now we ________ it as no good results have come out so far．

had been working; are still working

had worked; were still working

have been working; have worked

have worked; are still working

“You can’t catch me!” Janet shouted, ________ away．

run

running

to run

ran

Sales of CDs have greatly increased since the early 1990s, when people ________ to enjoy the advantages of this new technology．

begin

began

have began

had began

More patients ________ in hospital this year than last year．

treated

have treated

had been treated

have been treated

I ________ you not to move my dictionary－now I can’t find it．

asked

ask

was asking

had asked

My mind wasn’t on what he was saying, so I’m afraid I ________ half of it．

was missing

had missed

will miss

missed

I can’t stand ________ with Jane in the same office．She just refuses ________ talking while she works．

working; stopping

to work; stopping

working; to stop

to work; to stop