填空

       Here  1  (be) the results(结果)of the student activity (活动)survey (调查)at Hilltop High School.

Most   2  (student) exercise three or four   3  (time) a week. Some students   4  (exercise) once or twice

a week. Some students exercise every day.

       As for   5   (homework), most students   6   (do )homework every day. Some students do homework three or four times a week. Few   7   (student) do homework once or twice a week.

       The results for “watch TV”  8   (be) interesting. Some students  9   (watch)TV once or twice a

week, some students never watch TV, some students watch TV every   10   (day).

如果用颈内动脉速度/颈总动脉速度作为诊断近端颈内动脉狭窄的指标，以下哪个收缩期峰值流速比值，提示颈内动脉管径狭窄率超过70%（）。

A.1.5

B.2.0

C.4.0

D.5.0

E.5.5