— Mom, the door ____. My keys are locked in it again.

— You ____ it! I told you always to carry your keys with you. [ ]

A. can't open; have asked for

B. wouldn't be opened; asked for

C. won't open; asked for

D. can't be opened; are asking for

如果水源水中含有NO²－N和NO₃－N，说明水源（）。

A、已完全自净

B、没有被污染过

C、自净作用接近完成

D、污染较严重