对不起，实在找不到题号，是新东方的题目，请NN看一下

今天心太黑了，想把SC全部总结完，发现不行了，只是粗过了一遍。做新东方材料时发现有一题不是OG上的有两个答案，我和GG的意见也不一，想请牛牛给看一下，我选A，GG选E。

Geologists believe that the bering land bridge, over which human beings are thought to have first entered the American,disappeared about 14,000 years ago when massive glaciers melted and caused the sea level to rise several hundred feet worldwide.

A.are thought to have first entered

B.were thought first to enter

C.were thought at first to enter

D.are thought of as first entering

E.were thought to first enter

谢谢！

支持MM的选择，选择A。

（1）.are thought，一般现在时从逻辑意思上最贴切。

（2）不定式完成时，表示不定式的动作发生句子谓语之前，正好符合本句的逻辑意思。

A is fine.

E implies that human were thought to do sth, but they are now not thought to do the same thing.

时态中的科学研究用现在时态.所以选择A我是这么理解的

今天有朋友问B和E的区别。

我想讲一下我的想法。我觉得这道题应该是考时态和就近修饰这两点。

时态，我觉得上面的朋友已经完全说出了我的想法。

至于B和E的差别，在于考察first到底是修饰什么，从句意来判断，应该是人类第一次进入的意思，所以first 要尽量靠近它的修饰语enter。

希望我已经解释明白。不当之处，请指正。