—Tom, you didn’t come to the party last night?                              — I _____ , but I suddenly remembered I had homework to do.

In the past few years, sea ice ____ in the Arctic as a result of global warming.

By the time our teacher arrives tomorrow, all the work _____,with which he will be content.

Before joining the Department of Defense, Mr． Panetta _______ as director of the CIA from February 2009 to June 2011．

The timetable says the school bus _________ here for the first trip at 6:30 am.

—Where is your brother?   —He has gone to Beijing. He         back in three days.

 The geography teacher told his student that the earth ________around the sun .

When _____ the letter, tears came to her eyes.

His father told me that he ____  for the United States three days _______.

–How was your trip abroad?–Great. The only pity is that I ______to buy some gifts for my friends.

 He said that his car __________ stolen and he ________ have to telephone the police.

The three of us ________ around Europe for about a month last summer.

-—David has gone to Australia on business.—Really? I ______ why he was absent from today’s meeting.

Exciting as its special effects are ______, there is too much violence in the film.

We were told not to touch the equipment in the laboratory unless ________.

The rate of racial progress varies in different areas of the country, but in the past ten years _________ more improvement.

 For some time, Chinese people, under the leadership of CPC, ________ the contents of the Scientific Development Concept in the course of practicing socialism in China.

—I'm sorry. I shouldn't have been so rude to you.—You ________ something not very nice to me, but that's OK.

Instead of flocking into the cities, the peasants __________ villages and townships of a new type in the past few years.

Jack doesn’t smoke now, but he ______________ for almost twenty years.