885 sec 21-16

kjhggsdf

16. New techniques in thermal-scanning photography, a process that records radiation from surface areas, makes it possible to study the effects of calefaction, or warming, of a river in greater detail than ever before.
(A) makes it possible to study the effects of calefaction, or warming, of a river in greater detail than ever before
(B) make it possible to study, in greater detail, the effects of calefaction, or warming, of a river than ever before
(C) have made it possible to study in greater detail than ever before the effects of calefaction, or warming, of a river
(D) make possible the study of the effects of calefaction, or warming, of a river in greater detail than it ever was before
(E) has made it more possible than ever before to study in greater detail the effects of calefaction, or warming, of a river

ANSWER C. What is wrong with B?

想请问一下   从哪一句话  可以判断出  要用現在完成式  ??? 谢谢

kjhggsdf

那我想再请问一下  是不是所有只要出现  then ever before  都要用完成式呢

The finacial crash of October 1987 demonstrated that the worled's capital markets are more closely integrated than ever before and that events in one part of the global village may be transmitted to the rest of the village-almost instsantaneously.

我在別的文章中 看到这一句话  就是不用完成式的 

????

goodfishs

有than ever before，应该用完成时，表示到目前为止都能study the effects of calefaction of a river in greater detail