Question:
Do you lay down --- or lie down for a nap before dinner?
如果你没有查询昨天两个问题中关于lay 和 lie 的用法不同，请记住：
Lay means to place or put something or someone somewhere.
Lie means to recline, rest or remain.
如果这两个词的意思分清楚了，可能还会遇到的麻烦是过去式和过去分词：
lie lay have lain
lay laid have laid
所以其实分辨出两个词的意思，再稍微记忆一下分词的区别，就不会有什么问题啦。
另外一组词是effect affect, 我觉得作者讲的也非常清楚：
An effect is an idea or thing --- a scenic effect; what a stunning effect she produces; this will have a bad effect on production. Affect, on the other hand, is a verb meaning to change, influence, move, or pretend --- this will affect production; she affects every strangely; his tears do not affect me; he affected a southern accent after he returned from Georgia. However, and be careful of this, if your verb has the special meaning of bring about, spell it effect --- we shall try to effect(bring about) an improvement in production.
大多数情况下，effect是名词，affect是动词，但是有一种情况例外：在表达bring about 这个意思的时候，一定要用effect.
child's play
something that is easy to do
= a piece of cake
