拉伸体<img src="http://jgxm-question.oss-cn-beijing.aliyuncs.com/psst/files/6911649819ff44d9b04d0bc3303fde30.png?x-oss-process=image/sharpen,200"/>的动平面如图a所示，其正确的轴测图是:<br/> <img src="http://jgxm-question.oss-cn-beijing.aliyuncs.com/psst/files/e0aaa533cae74e0fbbe9d91cf38cd59d.png?x-oss-process=image/sharpen,200"/>