get together for a big dinner与for good luck 中的for怎样理解

Question

今天学了这两个句子，可没听明白里面重点的for的意思，（比如说是介词，有何作用等）请帮忙讲解一下，这是仁爱英语七年级下册的 急求！

Answer 1

to do不定式表目的，相当于 for+名词
The family get together for a big dinner =The family get together to have a big dinner .
For good luck =to have a good luck

Answer 2

for在这里作介词，表示目的，可理解为“为了。。。”追问

老师好像不是这么讲的 是什么他还等于带to的不定时之类的 麻烦讲解一下

追答

get together for a big dinner 相当于get together to have a big dinner
to do 经常表示目的，有时可以替换 for

Answer 3

1.PREP

(表示对象)为了，给，对于 If something is for someone, they are intended to have it or benefit from it.
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...that intense need to care for your baby.

那种想要照顾自己婴儿的迫切需要