题干
It’s time to say goodbye to my school. I’ll always remember the people __
have helped me.
have helped me.
A：who
B：what
C：which
D：where
答案(点此获取答案解析）
A
”和“ 
”代表两种不同的单质分子，它们在一定条件下能发生如图所示的化学反应，下列说法正确的是（ ） 