Have you ever listened to the song Yesterday Once More, ________ singer died in her early years?
A:its
B:it's
C:whose
D:which
若m2+mn=﹣3,n2﹣3mn=﹣12,则m2+4mn﹣n2的值为____ .
图是“我国风能资源分布示意图”,读图完成
A.大声呼救
B.用硬物敲击预制板或墙壁,向营救人员求救
C.见缝就钻,说不定能从废墟中爬出来
D.静下来等待营救人员来救
说明理由:____.