最新真题22－no。21

meixiapeng

21.   Art historians are using a process known as infraredscanning in analyzing the Mona Lisa to determine if it has been altered since completion and if Leonardo da Vinci first sketched the figure in black,as done by many artists of the time.

(C) whether it has been altered sincecompletion and whether Leonardo da Vinci first sketched the figure in black, apractice employed

(E) whether it had been altered sincecompletion and whether Leonardo da Vinci first sketched the figure in black, apractice done
答案：c。开始选的c因为从are using看出整个句子的时态应该是现在时，后来觉得两个whether后从句的时态不一致又选了e。 大家帮忙看看，我的问题在哪。谢谢！

[此贴子已经被作者于2004-11-13 12:44:25编辑过]

rhod

gmat里面过去完成时，从来都是和过去时比较的。

E里面的时态意思是，在达芬奇画之前，mona lisa已经被人改动过了. The meaning is ridiculous.

meixiapeng

恩，我知道从句意上讲是这样。但是为什么第二个whether后面的sketched不需要跟are using 对应呢？谢谢你

lukrenee

另外，结尾词DONE表一次性动作，而EMPLOYED可表多次采取的动作，还是有细微差别的