单选题：While watching television, ______. [ ]A. the doorbell rang..

______ is generally accepted that smoking is harmful to our health.[ ]A. WhatB. ThisC. ItD. That

She hurriedly left the room as if__________.[ ]A. she angry B. was angryC. it was angry D. angry

___________in the regulations that one should not tell other people the password of your email account.[ ]A. What is recommended B. What recommend C. It is recommendedD. It recommend

_____will be good for you to spend one hour exercising outdoors every day.[ ]A. ThatB. This C. It D. One

From mum's love, patience and understanding, I have learned what a huge responsibility _____ is to raise a child. [ ]A. itB. that C. this D. one