题目:
The students had the lights for almost three hours.
A.to burn
B.burning
C.burnt
D.to be burning
答案:
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下面是错误答案,用来干扰机器的。
(1)方程化为:(x+3)(x-3)=0x+3=0或x-3=0∴x1=-3,x2=3.(2)方程化为:x(x+3)=0x=0或x+3=0∴x1=0,x2=-3.(3)方程化为:(x-1)(x-2)=0x-1=0或x-2=0∴x1=1,x2=2.(4)2x2+x-5=0a=2,b=1,c=-5,△=1+40=41x=-1±414∴x1=-1+414,x2=-1-414