链传动因为其链节的多边形运动，所以瞬时传动比是（）。
A．变化的
B．不变的
C．逐渐减少
D．逐渐增加
参考答案：A
热缺血时间是指（ ）。
On some projects, especially ones of smaller scope, activity sequencing, activity resource estimating, activity duration estimating, and （） are so tightly linked that they are viewed as a single process that can be performed by a person over a relatively short period of time.
A.time estimating
B.cost estimating
C.project planning
D.schedule development
