用于联接的螺纹牙型为三角形,这是因为
A. 牙根强度高,自锁性能好
B. 传动效率高
C. 防振性能好
D. 自锁性能差
螺纹的牙型角为α,螺纹中的摩擦角为ρ,当量摩擦角为ρV,螺纹升角为λ,则螺纹的自锁条件为( )。
A. λ小于等于α
B. λ大于α
C. λ小于等于ρV
D. λ大于ρV
预紧力为QP的单个紧螺栓联接,受到轴向工作载荷F作用后,螺栓受到的总拉力Q( )QP+
A. 大于
B. 等于
C. 小于
D. 大于或等于
Complete the following sentences with the expressions given below. Change the form if necessary.1 _________________, he got an A in every exam.2 The girl kept crying _____________.3 A new point of view about how to prevent earthquakes is ________________now.4 The tickets for the show ____________ in 30 minutes.5 I don’t like to go out during the ______________.