The English physician Edward Jenner found that if experimental subjects were deliberately infected with cowpox, which caused only a mild illness, they are immune from smallpox.


which caused only a mild illness, they are immune from

causing only a mild illness, they become immune from

which causes only a mild illness, they are immune to

causing only a mild illness, they became immune from

which caused only a mild illness, they would become immune to

考题讲解

题目分析:
略。

选项分析:

A选项:由于they are immune from smallpox是一个虚拟的情况,即,它是存在于“实验者感染cowpox”的情况下的,因此,其应该用虚拟语气,即,they would become immune from smallpox。

B选项:分词短语causing only a mild illness是伴随状语,其主语为它所修饰的句子的主语,即,experimental subjects。但在逻辑上,引起疾病的应该是 cowpox,而不是experimental subjects。

C选项:本选项错误同选项(A)。

D选项:本选项错误同选项(B)。

E选项:Correct. 本选项在语法和逻辑上均是正确的。

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