Question

sat 语法题

A cure for some kinds of cancer, 【scientists believe, may be】 found within the next decade.
A。原句
B。scientists believe they may be
请问，B错在哪？

Answer 1

原句中scientists believe 是插入语，不影响整句的意思。原句的主语是 A cure for some kinds of cancer, 谓语动词 may be found, within the next decade为状语，表示时间。
A cure for some kinds of cancer, （scientists believe, ）may be found within the next decade.

B句中，they的指代就不明确了。被发现的是一种方法，而不是科学家们。如果要用科学家作主语则可这样说：
Scientists believe (that) a cure for some kinds of cancer may be found within the next decade.

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