1.The population density per square mile in the United States is twenty-two people,___________ .

　　2. The computer being a useful tool in serving the people, we should do our best __________ .

　　3. Thompson had a hard time __________ in the new country.

　　4. It was a small country house but it was large __________ .

　　5. You __________ ;our teacher only asked for 300 words, and you have written 400!

　　参考答案：

　　1　while that in Canada is two

　　2　to have a good command/ mastery of the computer science

　　3　 getting used to the climate and customs / adapting himself to the climate and customs

　　4　by urban standards

　　5　neednt have written such a long essay