—Have you ever seen Zhou Libo’s talk show?—Yes. It's very funny and it often makes people .
A:to laugh
B:laugh
C:laughing
在湖边高出水面50 m的山顶A处看见一艘飞艇停留在湖面上空某处,观察到飞艇底部标志P处的仰角为45°,又观其在湖中之像的俯角为60°.则飞艇离开湖面的高度( )