The box was very heavy, but Tom still ( ) to carry it home.
A. manage
B. manager
C. managed
D. management
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People close their windows at night in an attempt to shut( )the sound of gunfire(枪声).
A. on
B. in
C. out
D. up
You are asking ( )_ trouble if you let your child play with fire.
A. for
B. at
C. in
D. out
实数域上的二次多项式当判别式△满足()时不可约。
A. △<0
B. △>0
C. △<1
D. △=0
p(x)是R[x]上不可约多项式,如果p(x)的复根c是实数,那么p(x)是()。
A. 零次多项式
B. 一次多项式
C. 四次多项式
D. 三次多项式