I ______ my homework, don't talk with me. [ ]
A. am doing
B. is doing
C. do
D.can do
答案:A
要使x2-6x+a成为形如(x-b)2的完全平方式,则a,b的值为( )
A.a=9,b=9
B.a=9,b=3
C.a=3,b=3
D.a=-3,b=-2
如何破解“人质”战略?