将二次三项式x2+2x-2进行配方，其结果等于 ．
x2+2x-2=x2+2x+1-3=（x+1）2-3．
故答案为：（x+1）2-3
—— How about the cloth you bought yesterday?
—— That’s very beautiful. It ＿＿＿＿＿＿ so soft.
A．felt
B．feels
C．is feeling
D．fall
设天线的高度为h，两天线的水平间距为D，则η=h/D根据经验，对于水平分集天线间隔，η的最优值是（）
A.10
B.11
C.12
D.15
