for 是介词，后面接名词或动名词。
这个很简单 a lot 是指一种程度，意思相当于very much a lot of 是 多 的意思，相当于 lots
例句：
Thanks a lot for your books.
Tha′nks a lot for (joining ) us at the party.
Thanks for helping with my English
a lot of 和lots of 意思一样。都是修饰名次复数和不可数名词。也就是n. n.
例句：You should drink a lot of boild water.=You should drink lots of boild water.你应该多喝一些开水
我们可以说speak a lot"经常讲" 即V.+ a lot 表示频率 lots of + 可数/不可数名词。
