扫描二维码，直接登录
题库 / OG2018-SC-735
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
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。
cause only a mild illness可以用动名词，也可以用which从句来做定语修饰cowpox，但是如果causing only a mild illness前面加了逗号，就可以当做独立主格做状语，它的主语是experimental subjects，语义不对，可以排除BD。
另外整个that从句用的是虚拟语气，所以动词都要用虚拟形式。排除C和A。
登录 或 注册 后可以参加讨论