答案：B。应改为：concentrating on。have trouble in doing sth…，做什么事情有麻烦。
67. The course would [have been offered] this term, but it [cancelled]
A B
because too few students [had registered] before registration [closed].
C D
答案：B。应改为：was cancelled，被动语态。
68. [Even though] she looks very [young], she is [twice older than] my
A B C
[twenty-year-old] sister.
D
答案：C。应改为：twice as old as。
69.In the days when coal was so [widely] used, [no one] realized how
A B
soon and [how complete] oil would replace [it].
C D
答案：C。应改为：completely。soon和completely 修饰句中的动词replace。how修饰两个副词，soon 和completely并列。
70.[Those of us] who work in chemical [laboratories] should have [their]
A B C
lungs [checked] quite regularly.
D
答案：C。应改为our，代指前面的those of us。
Part IV Cloze
Tourism has become a very big 71 . For Spain, Italy and Greece it is the largest 72 of foreign exchange, and 73 for Britain, it is the fourth. Faced 74 this huge new income, no government can afford to look 75 on the business; questions of hotel bath rooms, beach umbrellas and ice-cream sales are now 76 by ministers of tourism with solemn expertise. Before the Second World War the tourist industry was widely 77 as being unmanly and stupid. But 78 has become a new industry, as trade business used 79 ; in Spain, Italy, Greece and much of Eastern Europe, new road 80 have opened up in the country, first to tourists, and 81 to industry and locals.
