“激光是电磁波，激光与生物组织的作用实质上是电磁场与生物组织的作用”属于（）

A.热作用

B.压强作用

C.光化作用

D.电磁作用

E.生物刺激作用

I got into trouble again. Only then ________ that I should have followed my parents’ advice.

A．I realized

B．did I realize

C．realized I

D．had I realized