沙脱平均直径
参考答案:
简称沙脱直径,其定义为若某一直径雾滴的体积与表面积之比等于全部取样雾滴的体积之和与表面积之和的比,则此雾滴的直径即为雾滴群的沙脱平均直径。
正常二尖瓣口面积为()。
A.1~2cm2
B.2~3cm2
C.3~5cm2
D.4~6cm2
E.6~8cm2
Li Lei told us that he _ never such a wonderful game before.[ ]
A. have; watched
B. had; watched
C. was; seen
D. will; seen