39. A president entering the final two years of a second term is likely to be at a severe disadvantage and is often unable to carry out a legislative program.
A. likely to be at a severe disadvantage and is often unable to
B. likely severely disadvantaged and often unable to
C. liable to e severely disadvantaged and can not often
D. liable that he or she is at a severe disadvantage and can not often
E. at a severe disadvantage, often likely to be unable that he or she can
答案是A，但是我不知道为什么likely to be at a severe disadvantage and （is） often unable to。 括号里的is为什么不能省略呢？既然前面已经有is 了，is likely to be at a severe disadvantage。
请大家帮助解释一下罗，谢谢拉！ | 
