51. If you have been generous to a person for a period of time, it is most likely that the person will take advantage of your generosity and trade on your “weakness” become appreciative of your kindness.

A. but not B.let alone C. rather than D. instead of

52. A poet must not write for the ages past, but for in which he lives and those which are to follow.

A. one B. those C. the one D. that

53. There is a delicate balance of nature many square miles of ocean and vegetation and clean air are needed to maintain only a relatively few human beings.

A. where B. in which C. when D. how

54. There are cases new factories are being put up and beautiful old trees are going to be cut down for a new factory.

A. which B. where C. that D. when

55. Somebody in the next room must be ill, a doctor has just come out.

A. because B. for C. in that D. as

51. Crather than 表示对比，在意思上前后形成对照：take advantage of your generosity…rather than become appreciative of your kindness意为“利用你的慷慨，而不是理解你的好意”。另外，rather than在结构上起并列作用，使take advantage与become appreciative平行。

52. Cthe one替代the age，还原为：…but must write for the age in which he lives and the ages which are to follow。

53. Bin which在定语从句中做状语，相当于in the balance of nature (many square miles of…)。

54. Cthat引导case的同位语从句，其他连接词都不合适。

55. Bfor连接一个原因分句，对前面的推测做原因上的解释。请考生记住：无论从逻辑推理还是从语法规则上看，只要前面是表示推测的句子，后面大都用for连接后一句，而不用其他连词。

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