区别野外采集的水样是硬水、还是软水，可选用（） A．明矾_爱下问搜题

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问题选择题

区别野外采集的水样是硬水、还是软水，可选用（　　）

A．明矾

B．活性炭

C．肥皂水

D．石灰水

答案

答案：C

选择题

如图所示，足够长的U形光滑金属导轨平面与水平面成θ角（0<θ<90°），其中MN与PQ平行且间距为L，导轨平面与磁感应强度为B的匀强磁场垂直，导轨电阻不计，金属棒ab由静止开始沿导轨下滑，并与两导轨始终保持垂直且良好接触，ab棒接入电路的电阻为R，当流过ab棒某一横截面的电量为q时，棒的速度大小为，则金属棒ab在这一过程中

A．加速度大小为

B．下滑位移大小为

C．产生的焦耳热为

D．受到的最大安培力大小为

完形填空

When I settled in Chicago，my new city seemed so big and unfriendly. Then I had a ___1___ problem and had to go to hospital for a ___2___ examination.
It seemed a small ___3___ compared to the one I was about to face, but things started to go ___4___ right from the beginning. Not having a car for ___5___ the city, I was depending on a couple of buses to get me from A to B. ___6___ I’d left myself plenty of time, soon it was ___7___ that I was going to be late, as I had mistakenly boarded a bus that was taking me in the ___8___ direction.
I ___9___ the bus and stood on the pavement not knowing what to do. I look into the eyes of a ___10___ who was trying to get past me. __11____ instead of moving on, she stopped to ask if I was ___12___. After I explained my ___13___ to her, she pointed to a bus stop across the street, where a bus would take me back into the city to my ___14___. Sitting there waiting, I felt ___15___ that someone had been willing to help. ___16___, hearing a horn (喇叭) nearby, I looked up to see a car with my new friend ___17___ at me to get in. She had returned to offer me a ___18___ to the hospital.
Such unexpected ___19___ from a passer-by was a lovely gift to receive. As I climbed out of the car at the hospital and turned to thank her, she smiled and told me not to lose ___20___, for all things are possible.

D．appreciating

B．Surprisingly

A．appointment

D．disappointed