再请教一道语法，万分感谢~

bhcrystal

246.
            (31468-!-item-!-188;#058&005866)     (GWD-9-Q27)

 

Scientists have identified an asteroid, 2000 BF19, that is about half a mile wide and, if it strikes Earth, it can do tremendous damage to part of the planet but probably not cause planetwide destruction.

A. and, if it strikes Earth, it can do tremendous damage to part of the planet but

B. and, if it would strike Earth, part of the planet could experience a tremendous amount of damage but it would

C. and that, if it were to strike Earth, could do tremendous damage to part of the planet but would

D. and that, if Earth is struck by it, can do part of the planet tremendous damage, but it would

E. and that, if it strikes Earth, it could experience a tremendous amount of damage but

答案选C，可是could do前面是不是要加it?

clementliang

Scientists have identified an asteroid, 2000 BF19, that is about half a mile wide and, if it strikes Earth, it can do tremendous damage to part of the planet but probably not cause planetwide destruction.

A. and, if it strikes Earth, it can do tremendous damage to part of the planet but

B. and, if it would strike Earth, part of the planet could experience a tremendous amount of damage but it would

C. and that, if it were to strike Earth, could do tremendous damage to part of the planet but would

D. and that, if Earth is struck by it, can do part of the planet tremendous damage, but it would

E. and that, if it strikes Earth, it could experience a tremendous amount of damage but

答案选C，可是could do前面是不是要加it?

  

    if it were to strike Earth 是插入语， that, if it were to strike Earth, could do tremendous damage to part of the planet but would

bhcrystal

看懂了。。。。。。。。。谢谢了~快考试了脑子都不转了