某线路有功、无功负荷均由母线流向线路，下面的角度范围正确的是（）。 A. B. C.

男，25岁，体重50kg，Ⅱ度、Ⅲ度烧伤总面积为60％，伤后第一个8小时所需晶体液和胶体液为（）。

A.2000ml

B.2250ml

C.2500ml

D.3000ml

E.4500ml

某同学用图甲所示的电路测绘额定电压为3.0V的小灯泡伏安特性图线，并研究小灯泡实际功率及灯丝温度等问题。

（1）根据电路图，将图乙中的实验仪器连成完整的实验电路。 

（2）连好电路后，开关闭合前，图甲中滑动变阻器R的滑片应置于____________（填“a端”、“b端”或“ab正中间”）。

（3）闭合开关，向b端调节滑动变阻器R的滑片，发现“电流表的示数为零，电压表的示数逐渐增大”，则分析电路的可能故障为____________。

A．小灯泡短路

B．小灯泡断路

C．电流表断路

D．滑动变阻器断路

（4）排除故障后，该同学完成了实验。根据实验数据，画出的小灯泡I--U图线如图。形成图中小灯泡伏安特性图线是曲线的原因为____________。

（5）根据I--U图线，可确定小灯泡在电压为2.0V时实际功率为____________。（保留两位有效数字）。

（6）已知小灯泡灯丝在27℃时电阻是1.5Ω，并且小灯泡灯丝电阻值与灯丝温度的关系为R=k(273+t)，k为比例常数。根据I--U图线，估算该灯泡正常工作时灯丝的温度约为____________℃。

关于弹力，下列说法中不正确的是（ ）

A．形变微小时，弹力很小

B．形变量越大，弹力就越大，弹力大小总是与形变量成正比的

C．放在水平桌面上的书对桌面的压力就是物体所受的重力

D．通常所说的压力、支持力和绳的拉力都是弹力

Yellowstone Weather

Yellowstone National Park is at high altitude. Most of the park is above 7,500 feet (2,275 meters).

Yellowstone’s weather is unpredictable. In summer, it may be warm and sunny with temperatures in the high 70F. At night in any given month, the temperature may drop close to freezing. So it is best to come prepared for cold evenings and mornings, especially if you are camping or hiking. When you leave your campsite, please leave it prepared for possible thundershowers and wind.

A sunny warm day may become fiercely stormy with wind, rain, sleet and sometimes snow. Without enough clothing, an easy hike or boat trip can turn into a battle for survival.

Seasonal Weather Information

Spring

Cold and snow continue into May, although temperatures gradually climb Early in spring, daytime temperatures average in the 40F to 50F; by late May and June, they may reach the60F and 70F. Nighttime lows fall below freezing.

Summer

Daytime temperatures are usually in the 70F, occasionally reaching the 80F in the lower elevations (高度). Nights are cool, temperatures may drop in the 40F and 30F—sometimes even the 20F. June can be cool and rainy; July and August tend to be somewhat drier, although afternoon thundershowers are common.

Fall

Weather can be pleasant, although temperatures average 10-20 degrees lower than summer readings. Nighttime lows can fall into the teens and lower. Snowstorms increase in frequency as the weeks go by or towards the end of the fall season.

Winter

Temperatures often stay near zero throughout the day, occasionally reaching high in the20F. Subzero nighttime lows are common. Annual snowfall averages nearly 150 inches in most of the park. At higher places, 200-400 inches of snow have been recorded.

The author writes this passage most probably for those who plan to () in Yellowstone National Park.

A．do research work

B．take a business trip

C．have sports games

D．spend their holidays or take a tour

与确定组织在一定时期的目标、制定战略和政策、制定规划、合理分配资源有关的信息属于（）。

A.控制信息

B.管理信息

C.计划信息

D.作业信息