gwd17-32

gmatplayers

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.

1. a reasonably clear picture has emerged of the patterns and causes of ocean currents
2. a reasonably clear picture of the patterns of ocean currents and their causes have emerged
3. a reasonably clear picture emerged of ocean currents, their patterns and the causes of them
4. there have emerged a reasonably clear picture of the patterns of ocean currents and what caused them
5. there had emerged a reasonably clear picture of the patterns of ocean currents and their causes

   Answer: is A    why? thanks

xionghuixhs

B。主谓不一致。picture...has emerged

C。their,them指代不明

D。E就不说了吧

chenjinchent

我觉得A的时态不一致

B的主语是pictures and causes 用have emerged是没有错的呀

NN们请教!

autumnjin

B的主谓没错，但their可以指代Patterns也可以只待causes，所以错.

qingdaonycS

b主谓不一直呀，主语picture...谓语have emerged
C的表达有问题吧picture emerged of ocean currents，应该是picture of

ocean currents emerged吧

albertjerrys

B的主语应该是pitcure,因为有of存在，所以应该连接their causes。

如果硬要理解成pictures and causes 就会产生逻辑问题。文中是说近半个世纪pictures出现，而causes是个客观现象，是一直存在的，不是近半个世纪才出现的。

还有这里的their我觉得指代没有问题，应该指代currents。首先符合逻辑意思，其次根据语法规则代词优先指代主语中心词。

rabbitbugs

E,大家能讲讲为什么不对么？it is.....that...强调结构；there had

done+主语  倒装结构；而且E还回避了A中的 the patterns and causes of

ocean currents的歧义问题，为何不选择E

另外，同意B选项从句主语是picture所以have 不对！