大全-155

1.       Aviation
officials have not only failed to determine the cause of the crash, but they
have also ignored demands by the pilots union that the investigation should be
expedited.

(A) crash, but they have also
ignored demands by the pilots union that the investigation should be expedited

(B) crash but also ignored demands
by the pilots union that the investigation be expedited

(C) crash but have ignored demands
for expediting the investigation by the pilots’ union

(D) crash, but they are also
ignoring the pilots’ union’s demands to expedite the investigation（B）

是B的but also吧。

but also在引导independant的句子的时候前面才要加逗号。也就是说，当but also后有主+谓结构时才要“,”

这是我个人做题的感觉，希望其他NN指正