请教大全No.446(时态问题）

这题答案是A,但是我不明白为何不是用将来时态呢？因为这是15年后的事情，所以我选了C,尽管我知道know as being  不是特别好，但是我实在不明白A中的时态，望指教！！！

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

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

"It may be" is just the possibility, so it does not relate with the "willing" future tense.

"known to be" is absolutely the best to express.

以下是引用mmfoolish在2005-8-31 7:00:00的发言：
楼上的，谢谢了！还有一个问题，again的位置有什么讲究吗？在上面的答案中，好像again的位置有所区别

同问again的位置？