低钾血症时，最早出现的临床表现是A．心电图改变B．肌无力C．口苦、恶心D．心脏传导阻

某同学做“测量金属丝电阻率”的实验。

（1）首先，他用螺旋测微器在被测金属丝上的三个不同位置各测一次直径，并求出其平均值作为金属丝的直径d。其中某次测量如图所示，这次测量对应位置金属导线的直径为__________mm；

（2）然后他测量了金属丝的电阻。实验中使用的器材有：

a．金属丝（长度x₀为1.0m，电阻约5Ω~6Ω）

b．直流电源（4.5 V，内阻不计）

c．电流表（200mA，内阻约1.0Ω）

d．电压表（3V，内阻约3kΩ）

e．滑动变阻器（50Ω，1.5A）

f．定值电阻R₁  (5.0Ω，1.5A）

g．定值电阻R₂  (10.0Ω，1.0A）

h．定值电阻R₃ （100.0Ω，1.0A）

i．开关，导线若干

该同学实验时的电路图如图所示，且在实验中两块电表的读数都能接近满偏值，定值电阻应该选_____________（选填“R₁”、“R₂”或“R₃”）；

（3）设法保持金属丝的温度不变，而逐渐减小上述金属丝（长度为x₀）接入电路的长度x，当电压表的示数保持不变时，下列图象中正确反映了金属丝电阻消耗的功率P随x变化规律的是_________。

已知：3x²y^m+n与2x^2my³是同类项，则2m-n=______．

关于下肢静脉曲张症，下列叙述错误的是（）

A.下肢静脉曲张症多见于久站职业者

B.目前分类为原发性与瓣膜功能不全两种

C.凡下肢静脉曲张症者，Perthes试验多为阳性

D.小腿皮肤常见有色素沉着或经久不愈的溃疡

E.手术治疗是本病的主要手段

It’s easy to see how to help others, but what about those whose needs aren’t so obvious? This story may have happened a while back, but it was a lesson which has stayed with me and helped me ever since.

It was Thanksgiving and I was volunteering with my parents at a shelter for the poor. We stood behind the counter dishing out hot food to whoever came in. most of our dinners looked like they had been having hard times, their clothes old, worn and dry. In short, they looked poor!

Then, a man came in, who looked anything but poor. He was well dressed, wearing an expensive suit. I wondered what he was doing there and my jaw dropped in amazement when he joined the line for food. The closer he came to my service station, the more I muttered. What was this man doing? I wanted to know. Surely he wasn’t gong to take food.

Then my mother quietly took me to one side. She said, “You have assumed that the needs of the people who come here must be purely physical: hunger, inadequate shelter and needs are emotional? What if he needs comfort, friends, or just to be among other human beings?” her words hit me like a ton of bricks! I felt like I should apologize to the man, but I didn’t.

About a week later the shelter received a large donation from an anonymous source. I can’t help but wonder if it came from that man.

Now, whether I meet others, I remember my mother’s words and try to send kindness and blessings to them, regardless of how they look.

Needs aren’t always visible. But kindness always makes a difference.

小题1:The task of the author at the shelter was to_______.

A．decide whether dinners looked poor

B．learn life experience there

C．serve hot food to the poor

D．help parents order dishes小题2:When the man waited in line, how did the author feel?

A．Surprised

B．Pitiful

C．Excited

D．Angry小题3:The author felt he should apologize to the man, because he_______.

A．was asked to do so by his mother

B．gave the man food much less than others

C．realized something was wrong with the man

D．knew later that the man went there to donate小题4:What can we infer from the last paragraph?

A．We should show others kindness whatever their needs are

B．Some needs can’t be known clearly at times

C．Needs can always be met by kindness

D．We should find out others’ needs

正常妊娠期间泌尿系统的改变，下列说法正确的是（）

A.仰卧位尿量增加

B.夜尿量少于日尿量

C.肾血浆流量增加，肾小球滤过率增加

D.孕妇易患急性肾盂肾炎，以左侧多见

E.肾小管对葡萄糖的再吸收能力与肾小球滤过率相应增加