[求助]大全446

It may be another fifteen years before spacecraft from Earth again venture to Mars, a planet now known to be cold, dry, and probably lifeless.

(A) again venture to Mars, a planet now known to be

(B) venture to Mars again, a planet now known for being

(C) will venture to Mars again, a planet now known as being

(D) venture again to Mars, a planet that is known now to be（A）

(E) will again venture to Mars, a planet known now as being

答案A  这题不会。为什么不能用将来时呢？在飞船再到火星之前要花15年，飞船不是还没去吗？还有大全注释上说spacecraft复数，单复数对这题有什么影响吗？

用排除法的话可以得出 A，

a planet now known to be中省略 that is, be known to do固定短语，now 须放在动词之前

故只有A项符合

至于时态的问题我也搞不懂

还是请大N解答吧~~~~

用排除法的话可以得出 A，

a planet now known to be中省略 that is, be known to do固定短语，now 须放在动词之前

故只有A项符合

至于时态的问题我也搞不懂

还是请大N解答吧~~~~

好像是现在时态叙述宇宙飞船从地球到火星大概要15年。。。