He is so full of hot air.
他真是满口空话。
full of hot air 直译过来就是：“充满了热空气”。在英语俚语中，hot air是“空话，大话和夸夸其谈”的意思。所以这个短语的正确意思是：“满口空话，吹牛，夸夸其谈”。因此，当美国人说"He is full of hot air."时，他/她要表达的意思就是:"What he says is just empty talk."、"He is shooting off his mouth."、"What he says is all jaw."。
情景对白：
Shirley: He is ready enough with his promises, but often fails to carry them out.
雪莉：他总是满口许诺，但常常不履行。
Jane: Just ignore him. He is full of hot air.
简：别理他，他总是满口空话。
搭配句积累：
①He is generally regarded as a disgusting guy.
大家都认为他是个讨厌鬼。
②What he said is simply not credible.
他的话一点也没可信。
③Never believe in his commitment.
千万别相信他的承诺。
④Don't listen to him.
别听他的。
单词：
1. be all jaw 全是空话，废话连篇
All this could be all jaw without a government that is unified in opinion.
如果没有一个思想统一的政府来指导发展，实现这一切只是空谈一场。
What he said is all jaw.
他说的全是空话。
2. commitment n. 承诺，保证
We made a commitment to keep working together.
我们承诺继续合作。
They made a commitment to peace.
他们承诺要维护和平。
He made a commitment to pay the rent on time.
他保证按时付房租。
