请教各位托友！！

1.As many as 50 percent of the income from motion pictures produced in the United States comes from marketing the films abroad.

答案是A.如何改法？？as much as, income不可数

2.Eleanor Roosevelt set the standard against which the wives of all United States Presidents since have evaluated

答案是D，我的改法是将have改为being,因为since在此处作介词。

since能做介词用吗？个人觉得改为have been evaluated

3.When the Sun, Moon, and Earth are alignment and the Moon crosses the Earth's orbital plane, a solar eclipse occurs.

答案为B，如何改？？改为aligned，alignment是名词