英语口语是否有开头用"say"的习惯???

You can use say when you want to discuss something that might possibly happen or be true.
就是把say放开头表示你想要说那些事情很可能发生或者可能正确
比如Say you could change anything about the world we live in, what would it be?
相当于suppose

say可以在口语中当作一个很普通的词来使用，意思相当于if。
但是如果有些人乱用的话也可能。