用配方法解方程:x2+4x+1=0
x1=-2; x2= --2
——Can you go to the Great Wall with us next week?
—___________.[ ]
A. Yes, I can't
B. Sure, I'd love to
C. Sorry, I don't
D. No, I can
已知混凝土的设计配合比为C∶S∶G∶W = 439∶566∶1202∶193,经现场测定砂子的含水率为3%,石子的含水率为1%,则1m3混凝土拌合物的用水量为()kg 。
A.151
B.164
C.176
D.181