SAT几道改错题 At the age of seventy-one,legendary country music artist JC astonished his fans by performing a song that the rock group Nine Inch Nails orginally (has recorded).为什么has recorded 错了?怎么改?Today in class we discussed the common,but mistaken,assumption that when two people are no longer dating they are incapable (to be )friends.为什么to be 错了?怎么改?A great gray owl (flying low) across a forest clearing,its (wings beating) quietly and its ultrasensitive

SAT几道改错题
At the age of seventy-one,legendary country music artist JC astonished his fans by performing a song that the rock group Nine Inch Nails orginally (has recorded).
为什么has recorded 错了?怎么改?
Today in class we discussed the common,but mistaken,assumption that when two people are no longer dating they are incapable (to be )friends.
为什么to be 错了?怎么改?
A great gray owl (flying low) across a forest clearing,its (wings beating) quietly and its ultrasensitive ears turned to the faint sounds made by smalll creatures concealed under leaves.
我觉得wings beating 错了,beating 应该改成beat才能和and后面平行,为什么答案写的是flying low错了?
（Determined to) make a name for herself as a writer of short stories,Helen never submits anything to an editor until (revising) it several times.
我选的是determined to,为什么错的是revising?determined 不应该改成determing么?
还是感觉第三句有点怪怪的……如果前面前半句是主句的话and前面不应该加逗号吗？而且判断哪边是重心这种事情感觉也太难了吧……虽然我那种改法逗号后面少了and也不对……
能再麻烦仔细讲讲第三句吗？