They have some problems ____ for the party.A, prepareB, to prepar_其他解答

They have some problems ____ for the party.
A, prepareB, to prepare C, prepared D, preparing
答案是D,怎么解释?

人气：461 ℃　时间：2019-08-31 17:58:02

解答

have problems in doing something
在做.的时候有麻烦或者问题,但是介词in一般省略,所以选最后一个