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　　Prepare for the GMAT Exam - Test Prep Materials - GMAT Exam Practice Questions

　　题目

　　Unlike transplants between identical twins, whose genetic endowment is the same, all patients receiving hearts of other organs must take antirejection drugs for the rest of their lives.

　　选项

　　A. Unlike transplants between identical twins, whose genetic endowment is the same

　　B. Besides transplants involving identical twins with the same genetic endowment

　　C. Unless the transplant involves identical twins who have the same genetic endowment

　　D. Aside from a transplant between identical twins with the same genetic endowment

　　E. Other than transplants between identical twins, whose genetic endowment is the same

　　答案：C

　　解题思路：

　　In A and B, the phrases beginning Unlike… and Besides… modify patients, the subject of the main clause; thus A absurdly states that Unlike transplants…, patients…must take…drugs, and B that all patients except for transplants…must take… drugs. In B and D the expression identical twins with the same genetic endowment wrongly suggests that only some identical twin pairs are genetically identical. In E, the construction Other than transplants…, all patients… must take… drugs illogically suggests, as in B, that some patients are transplants. Choice C, the best answer, solves these problems by using a clause introduces by Unless to describe the exception to the rule and a nonrestrictive clause beginning with who to describe the characteristic attributed to all identical twins.