Smack lips:
向往未来的欢乐
例句：
I smack my lips every time I think about us lying on a white sand beach.
每当我想到我们躺在白色沙滩上的情景，我就忍不住很高兴。
Bite one's tongue:
一言不发；保持沉默
例句
It's wise to bite our tongue on a controversial /ˌkɑːntrəˈvɜːrʃl/ issue.
对有争议性的话题，我门还是少说话为妙。
Bite one's lip:
不乱说话
例句：
I must learn to bite my lip.
我必须学会不乱说话。
