询问对方意图或愿望时常用shall I /shall we

Shall we sit here?Yes,let's.

状语从句

目的状语从句：so /so that/in order that/in case

Finish this,so (that)you can start another.

条件状语从句：if/unless/is long as/provided

If you have time,go with us then.

She won't do it unless you ask her to.

As long as you are happy,it doesn't matter what you do.

Provided (that)the ice is thick,we'll go skating.