题型:单项选择题 A型题 关于正常主动脉瓣口血流的频谱多普勒特点叙述错误的是()。A.主动脉瓣口多普勒频谱幅度比肺动脉瓣口血流的频谱高B.频谱呈窄带脉冲型C.从心尖五腔观检查为负向多普勒频谱D.收缩期出现E.收缩期和舒张期均出现 查看答案
题型:选择题 They must have gotten to the top of the mountain by now. They_____ before the sun rose. A.settled downB.set out C.took off D.turned up 查看答案