181，100，73，64，( )
A．56
B．60
C．59
D．61
参考答案：D
一束光垂直射到平面镜上，反射光与入射光之间的夹角是______度，如果将平面镜转动20度，反射光线转过的角度是______度．
—What a hard life my parents live!
—So do my parents.When I grow up, I ______ to make them live more happily. [ ]
A. try
B. tried
C. will try
D. have tried
