已知物体的主、左视图，判断哪组三视图正确（含细虚线）。<img src="http://jgxm-question.oss-cn-beijing.aliyuncs.com/psst/files/5612ed18e2bd4082a6e0cbba6c1f3a77.png?x-oss-process=image/sharpen,200"/