1. 掌掴;用巴掌拍;打…耳光
    If you slap someone, you hit them with the palm of your hand.

    e.g. He would push or slap her once in a while...
           他偶尔会推搡她或是打她的耳光。
    e.g. I slapped him hard across the face...
           我重重地掴了他一记耳光。

2. (友好地)拍(…的后背)
    If you slap someone on the back, you hit them in a friendly manner on their back.

    e.g. A large middle-aged lady slapped me on the back and said 'Nice to see you again.'
           一位身材高大的中年女士拍了拍我的后背说：“很高兴再次见到你。”

3. (迅速或马虎地)涂，抹，贴
    If you slap something onto a surface, you put it there quickly, roughly, or carelessly.

slap

    e.g. The barman slapped the cup on to the waiting saucer.
           酒吧服务生麻利地把茶杯放在了茶碟上。

4. (不合理或草率地)施加(赋税、禁令等)
    If journalists say that the authorities slap something such as a tax or a ban on something, they think it is unreasonable or put on without careful thought.

    e.g. The government slapped a ban on the export of unprocessed logs...
           政府贸然禁止出口未加工过的原木。
    e.g. Thankfully the Government still hasn't discovered a way of slapping a tax on love, sunshine or air.
           谢天谢地，政府还没有找到对爱情、阳光和空气课税的方法。

5. 打击;侮辱;一记耳光
    If you describe something that someone does as a slap in the face, you mean that it shocks or upsets you because it shows that they do not support you or respect you.

    e.g. 'The Sun' calls it a massive slap in the face for the United States government...
           《太阳报》称之为打在美国政府脸上的一记重重的耳光。
    e.g. Britons persist in treating any pay rise of less than 5% as a slap in the face.
           英国人坚持认为加薪不到 5%不啻于一种羞辱。

6. 轻微的警告;轻微的惩罚
    A slap on the wrist is a warning or a punishment that is not very severe.

    e.g. The fine they gave her is just more or less a slap on the wrist.
           他们对她开出的罚金不过是一个轻微的警告而已。