螺纹外观检查的内容是（）。
A.垂直度
B.表面粗糙度
C.平面度
D.位置度
参考答案：B
______ that it was going to snow, the climbers decided to put off their attempt on the highest peak.
A．Having been told
B．Having told
C．Told
D．Telling
绝对调节力维1.5D的+1.00DS远视者，阅读距离28厘米，需配用（）的近用镜作阅读。
A.+1.50D
B.2.50D
C.3.57D
D.4.75D
