单杠骑撑前回环前倒时前腿向前迈出主要是为了（）。
A、增加动量
B、加大重力矩
C、增加位能
D、加大惯性
参考答案：B
病变较软，鲜红色，边界清楚，表面光滑。镜下表现为上皮萎缩，有的为上皮 异常增生或原位癌
A．均质型红斑B．均质型白斑C．颗粒型红斑D．疣状白斑E．间杂型红斑
Why not _________ your teacher for advice when you don’t know __________ the problems?
A．ask, what to do with
B．to ask, how to deal with
C．ask, what to deal with
D．to ask, how to do with.
