航空运输企业的经济规模()。
A.随多种因素而变化
B.只随生产能力变化
C.长期稳定
D.随机变化
参考答案：A
光线l过点P(1，－1)，经y轴反射后与圆C:(x－4)2+(y－4)2=1相切，求光线l所在的直线方程.
Mike was called to come to the party, but he himself didn't _______ . [ ]
A. show around
B. show up
C. come out
D. put up
