if he so choosees这句中so是什么用法?

if he so choosees这句中so是什么用法? if so,什么用法 do so 是什么用法? he is not so much a singer as his brother is...so much是什么用法, if any ,if so ,if anything 的区别和用法. out in用法请尽量详细列出各种用法.例句：So if anyone tells you,‘There he is,o I so don't care "so"是什么用法 so did he 和 so he did 的区别是什么啊,so has he 和 so he has he passed the driving test.so ..everyone if he or so…as…的用法是什么? so,such用法顺口溜的意思是什么? so much so that 用法