PSC官员在检查载重线勘定条件时，要特别注意（）。 Ⅰ、关闭装置 Ⅱ、甲板排水设施

— I've had a stomachache for two weeks.

— You ____ to the doctor when it started. [ ]

A. must go

B. should go

C. ought to have gone

D. might have gone

交代作用过程中，（）为主要因素，重结晶作用中，（）为主要因素。

A、温度、压力

B、热液、温度

C、压力、温度

D、热液、压力

设f(t)为连续函数，且

，求f(t)

从事单件生产的企业，只能按照产品的件别归集生产费用，计算产品成本。

Suzie’s Discount Footwear sells all pairs of shoes for one price and all pairs of boots for another price. On Monday the store sold 22 pairs of shoes and 16 pairs of boots for $650. On Tuesday the store sold 8 pairs of shoes and 32 pairs of boots for $760. How much more do pairs of boots cost than pairs of shoes at Suzie’s Discount Footwear ？（）

A. $2.50

B. $5.00

C. $5.50

D. $7.50

E. $15.00