什么是公称直径?
参考答案:把管子与管路附件的直径划分为一系列直径等级,即为公称直径。
公称直径即为阀门内径,对于管子、管件既不等到于外径也不等于内径。
Observe that for the programmer, as for the chef, the urgency of the patron(顾客)may govern the scheduled completion of the task, but it cannot govern the actual completion. An omelette(煎鸡蛋), promised in two minutes, may appear to be progressing nicely. But when it has not set in two minutes, the customer has two choices-waits or eats it raw. Software customers have had (1)choices.
Now I do not think software (2) have less inherent courage and firmness than chefs, nor than other engineering managers. But false (3) to match the patron's desired date is much more common in our discipline than elsewhere in engineering. It is very (4)to make a vigorous, plausible, and job risking defense of an estimate that is derived by no quantitative method, supported by little data, and certified chiefly by the hunches of the managers.
Clearly two solutions are needed. We need to develop and publicize productivity figures, bug-incidence figures, estimating rules, and so on. The whole profession can only profit from (5)such data. Until estimating is on a sounder basis, individual managers will need to stiffen their backbones and defend their estimates with the assurance that their poor hunches are better than wish derived estimates.
空白(4)处应选择()
A.easy
B.difficult
C.simple
D.painless
存续期基金的交易时间是指开放日的().
A.9:30—15:00
B.9:30—17:00
C.9:00—17:00
D.9:30—15:00