complain/ kəm'pleɪn /

1.vi.
to complain (about sth) (to relevant person) (就某事)投诉

2.vi.
(grumble) (就某事)诉苦

3.vi.[医] 
to complain of sth 诉说某病痛

to complain to sb (about sth)
(就某事)向某人投诉
to complain that...
抱怨…