23. Ideally, the professional career diplomat should help in the ongoing maintenance of an effective American foreign policy despite changes in administration.

(A) in the ongoing maintenance of

(B) in the maintaining of

(C) maintain

(D) to maintain and continue（C）

(E) the maintenance of

是TO 省略了吗？其他HELP 的用法请指教！

谢谢！

对了 这里是省略了TO

另外 help的用法是help sb do sth help sb to do sth永远错