请教一个基本性的概念，谢谢！

请解释一下修饰的限定性和非限定性的具体含义和区别；

比如在定语从句中；

或其他情况等。

3x！

nonrestrictive clause beginning with who to describe the characteristic attributed to all identical twins.”

没有其它的相信说明啊？

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 introduced 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.

注意比较highlight部分的区别。