急求 GWD25-39!讨论版没有

Q39.

Navigators have known for thousands of years that the ocean

has variable currents, but it is only in the last half century that

a reasonably clear picture has emerged of the patterns and

causes of ocean currents.

A.     a reasonably clear picture has emerged of the patterns

and causes of ocean currents.

B.     a reasonably clear picture of the patterns of ocean

currents and their causes have emerged.

C.     a reasonably clear picture emerged of ocean currents,

their patterns and the causes of them

D.     there have emerged a reasonably clear picture of the

patterns of ocean currents and what caused them.

E.      there had emerged a reasonably clear picture of the

patterns of ocean currents and their causes.

答案是A   我怎么看不明白呢a reasonably clear picture has emerged of the patterns

and causes of ocean currents. 谁能帮我讲讲??

and causes of ocean currents. 谁能帮我讲讲??

有倒装吧

正常语序是

  a reasonably clear picture of the patterns and causes of ocean currents has emerged.

强调句型加部分倒装

a reasonably clear picture has emerged of the patterns and causes of ocean currents

我总觉得这个题目的答案不是最完美，把修饰picture的部分移到后面这么远的地方。。。of the patterns and causes of ocean currents会不会修饰歧义？