15. An awful crash between an express train and a bus _____ , however, occur the other day in Russia.A. does B. did D. has to D. had to
People have planted a great many trees in order to________ wind and sand in the desert.
—Which of those novels do you like most? —________.They are both expensive and of little use.
(2012年三亚高三模拟)English can help________people and make the stay in a foreign country easy and comfortable.
—The air is full of smoke and people are coughing. —It will get worse________the government does something about the pollution.
(2011年银川一中高三模拟)________,I have to put it away and focus my attention on study this week.