大全140,还不明

140. 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

请问为什么不用将来时?

1) spacecrafe单复数同形.在本题应理解为复数

2)时间状语从句和条件状语从句一般不能用将来时态,用现在时表示将来

3) be known as 和 be known to 两者含义不同

be known as :表被称为 eg. Mozart is known as famous musician.

be known to d表被知道某个信息