【正确答案】 D

【答案解析】mock：取笑，嘲笑。laugh at：取笑，嘲笑。It is unkind to laugh at a person who is in trouble．嘲笑有困难的人是不好的。smile at：笑(某人或某事)。What are you smiling at?你在笑什么?look down on：看不起。Small boys usually look down on little girls and refuse to play with them．小男孩常常看不起小女孩，因此不愿意跟她们玩。belittle：贬低；低估。 Don't belittle what he has achieved．不要贬低他所取得的成就。