A、It is useless to complain.
B、It is useless complaining.
C、Complaining is useless.
D、It is useless of complaining.
正确答案:D
答案解析:略

A、It is useless to complain.
B、It is useless complaining.
C、Complaining is useless.
D、It is useless of complaining.
正确答案:D
答案解析:略