直线AB的三面投影是否正确（ ）。http://image.zhihuishu.com/zhs/onlineexam/ueditor/201811/43791576c9d5433f8d99c48daadacbd3.png

选择棱锥被正垂面截切后正确的左视图。 A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201811/6f582ca8c21a4113a4470da4dc266075.png" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201811/65ae2f577aa14584ae75cc84ab3050c1.png" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201811/089db3476a0145e19cb4b135eb0437db.png" /> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201811/e60c72d724f74552963c93af681ca44d.png" />

下列碳正离子的稳定性最大的是（ ） A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201811/5ae2658f66544b629fdcabed52d5f957.png"> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201811/1cefba39460048ef898157ea2ebc28b4.png"> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201811/451893995c5e4c8f8109398975819582.png"> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201811/31d934d857664b5c8e554a3b9c0fde75.png">

下列哪味中药为桂枝 A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201811/1ecec46f5cb24d1fba6eda07816fff21.JPG"> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201811/6630610aa0cf4408832ccd382a3263e2.JPG"> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201811/862f3e2a8fb7477cba0e4142b90606da.JPG"> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201811/fb77e5e5386c43739e4ef959765e0dcd.jpg">

下列哪味中药为柴胡 A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201811/52f519e3210144ab87fef57fa951264a.jpg"> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201811/67ed1a0a3783414782a019ae69ea0581.jpg"> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201811/661692aff17840c4a892da13f70a78e8.jpg"> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201811/3f64d19bea8741acb95f5a5b1a9dc3ae.jpg">