计算雨水管渠的设计流量时，应选用（）。 A．降雨历时大于流域的集水时间时所对应的暴雨

已知小灯泡正常发光时的电阻为20欧，通过的电流为0.5安，则小灯泡发光时两端的电压为______伏．如果电源的电压为16伏，为使小灯泡正常发光，需要串联一个______欧的电阻．

—How are you today, Bob?

—I'm even ________ now. I don't think the medicine is good for me. [ ]

A. better

B. worse

C. happier

D. unluckier

Documentation of a software package is normally produced for two purposes.One is to explain the （） of the software and describe how to use them.This is known as （）because it is designed to be read by the user of the software.The other purpose of documentation is to describe the software’s internal composition so that the system can be maintained later in its lifecycle.Documentation of this type is knownas （）.

One is to explain the （） of the software and describe how to use them.

A．plans

B．cost

C．features

D．schedules

下列说法正确的是：（    ）

A．在100 ℃．101 kPa条件下，液态水的气化热为40．69 kJ·mol^-1，则H₂O(g)H₂O(l) 的ΔH ="+" 40．69 kJ·mol^-1

B．已知MgCO₃的K_sp = 6．82 × 10^-6，则所有含有固体MgCO₃的溶液中，都有c(Mg²⁺) = c(CO₃^2-)，且c(Mg²⁺) · c(CO₃^2-)= 6．82 × 10^-6

C．常温下，在0．10 mol·L^-1的NH₃·H₂O溶液中加入少量NH₄Cl晶体，能使NH₃·H₂O的电离度降低，溶液的pH减小

D．已知：

则可以计算出反应的ΔH为－384 kJ·mol^-1

透老空若有有害气体溢出时，应立即用木塞封闭。