Discarded plastic bags may become horrible serial killers for animals because of their incredibly slow decay.
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听力原文:According to Glazebrouk and Baldry, what was the color of the universe?
(28)
A. Light green.
B. Milky white.
C. Dark blue.
D. Colorless.
微分方程yy'=1的通解为
A. y=x2+C
B. y2=x+C
C. 1/2y2=Cx
D. 1/2y2=x+C
【B15】
A. so
B. to
C. as
D. such
设x2是f(x)的一个原函数,则f(x)=
A. 2x
B. x3
C. (1/3)x3+C
D. 3x3+C