I decided that the best way to do this was to become a flight attendant.这里的“was to become a flight attendant.”为什么用to do形式?还有 be doing与be to do怎么区分?

I decided that the best way to do this was to become a flight attendant.这里的“was to become a flight attendant.”为什么用to do形式?还有 be doing与be to do怎么区分?
I decided that the best way to do this was to become a flight attendant.
这里的“was to become a flight attendant.”为什么用to do形式?还有 be doing与be to do怎么区分?

I decided that the best way to do this was to become a flight attendant.这里的“was to become a flight attendant.”为什么用to do形式?还有 be doing与be to do怎么区分?
that引导宾语从句.
相当于the best way was .这里不定式充当表语.不能用be doing

be doing是正在进行的动作
be to do是将要做的动作