Be all mouth: 只说不做,只是嘴上发发狠而已 if you say sb is all mouth, you mean that they talk a lot about doing sth, but are, in fact, not brave enough to do it

Don't be scared of her. She won't hurt you---she's all mouth. 不用怕她,她不会对你怎样,她只是说说而已.

Down in the dumps: depressed, miserable 闷闷不乐,沮丧

I've been feeling a bit down in the dumps since I lost my job. 自从丢了饭碗我一直打不起精神来.