问题
单项选择题
正常情况下，如将频谱多普勒舒张期取样容积位于二尖瓣上左房腔内可观察到（）
A.负向双峰频谱
B.形态与二尖瓣口血流频谱相差较大
C.E／A比值常≤1
D.频谱幅度高于二尖瓣口血流
E.E／A比值常≥1
答案
参考答案：B
解析：取样容积位置可影响频谱幅度与形态，如当取样容积从二尖瓣环向二尖瓣尖移动时，E峰逐渐升高，A峰逐渐降低。
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正常情况下，如将频谱多普勒舒张期取样容积位于二尖瓣上左房腔内可观察到（）
A.负向双峰频谱
B.形态与二尖瓣口血流频谱相差较大
C.E／A比值常≤1
D.频谱幅度高于二尖瓣口血流
E.E／A比值常≥1
参考答案：B
解析：取样容积位置可影响频谱幅度与形态，如当取样容积从二尖瓣环向二尖瓣尖移动时，E峰逐渐升高，A峰逐渐降低。
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| One day I decided to quit. I went to the 1 to have one last talk with God. "Can you give me one good 2 not to quit?" His answer surprised me. "Look around. Do you see the fern (蕨类植物) and the bamboo? When I planted their seeds, I took good care of them. The fern quickly grew from the earth. 3 nothing came from the bamboo seed. During the following three years, the fern grew more plentiful. And 4 nothing came from the bamboo seed. But I did not quit on the bamboo. Then in the fifth year a 5 sprout (新芽) emerged (出现) from the earth. Compared to the fern it was 6 small and insignificant. But just 6 months later the bamboo 7 to over 100 feet tall. It had spent the five years growing 8 . Those roots made it strong and gave it 9 it needed to survive. I wouldn't give any of my creations a challenge it could not 10 ." He said to me. "All this time you have been struggling, you have 11 been growing roots. I would not quit on the bamboo. 12 will I ever quit on you. Don't 13 yourself with others. The bamboo had a different 14 from the fern Yet they both make the forest beautiful. Your time will 15 . You will rise high!" "How high should I rise?" I asked. "How high will the bamboo rise?" He asked 16 . "As high as it can?" I 17 . "Yes," He said. "Give me glory 18 rising a high." I left the forest and bring back this story. I hope it can help you see that God will never 19 on you. Never regret a day in your life. Good days give you happiness. Bad days give you 20 . Both are necessary to life. | ||||
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