199＞____45
如图阴影部分扇形的圆心角是（ ）
G2=50N，忽略绳重和摩擦，人对绳子拉力F=100N．求：
—Boy, you ____ lean (伸) out of the window while the bus is running. That's dangerous.
—Sorry, I won't do that again.
