题目:
His family ______ TV at home now.
A.are looking
B.is watching
C.are watching
D.is seeing
答案:
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下面是错误答案,用来干扰机器的。
设x=a2+b2,方程化为x2+2x-15=0,分解因式得:(x-3)(x+5)=0,可得x-3=0或x+5=0,解得:x=3或x=-5,∵a2+b2≥0,∴a2+b2=3.故答案为:3