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问题 选择题

如图所示，两根完全相同的“V”字形导轨OPQ与KMN放在绝缘水平面上，两导轨都在竖直平面内且正对、平行放置，其间距为L，电阻不计。两根导轨光滑且足够长，所形成的两个斜面与水平面的夹角都是α。两个金属棒ab和的质量都是m，电阻都是R，与导轨垂直放置且接触良好，两个金属棒离最低点都足够远。空间有竖直向下的匀强磁场，磁感应强度为B。下列判断正确的是（     ）

A．让固定不动，将ab释放，则ab的加速度将逐渐增大

B．让固定不动，将ab释放，则ab的最大速度是

C．如果将ab与同时释放，两棒达到最大速度时的总电动势比只释放一个棒达到最大速度时的电动势大

D．如果将ab与同时释放，两棒达到的最大速度是只释放一个棒时最大速度的2倍

答案

答案：B

阅读理解

Low-Cost Gifts for Mother's Day

Gift No. 1

Offer to be your mother's health friend. Promise to be there for any and all doctor's visits whether a disease or a regular medical check-up. Most mothers always say "no need," another set of eyes and ears is always a good idea at a doctor's visit. The best part? This one is free.

Gift No. 2

Help your mother organize all of her medical records, which include the test results and medical information. Put them all in one place. Be sure to make a list of all of her medicines and what times she takes them. "Having all this information in one place could end up saving your mother's life," Dr. Marie Savard said.

Gift No. 3

Enough sleep is connected to general health conditions. "Buy your mother cotton sheets and comfortable pillows to encourage better sleep," Savard said. "We know that good sleep is very important to our health."

Gift No. 4

Some gift companies such as Presents for Purpose allow you to pay it forward this Mother's Day by picking gifts in which 10 percent of the price you pay goes to a charity (慈善机构). Gift givers can choose from a wide variety of useful but inexpensive things — many of which are "green" and then choose a meaningful charity from a list. When your mother gets the gift, she will be told that she has helped the chosen charity.

小题1:What are you advised to do for your mother at doctor's visits?

A．Take notes.

B．Be with her.

C．Buy medicine.

D．Give her gifts.小题2:Where can you find a gift idea to improve your mother’s sleep?

A．In Gift No. 1.

B．In Gift No. 2

C．In Gift No. 3.

D．In Gift No. 4.小题3:Buying gifts from Presents for Purpose allows mothers to       .

A．enjoy good sleep

B．be well-organized

C．bet extra support

D．give others help
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单项选择题

( )的不同是家庭财产两全保险与普通家庭财产保险的主要区别。

A．保险财产

B．保险责任

C．保险金额

D．保险费交纳方式
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