不定项选择如图所示，光滑水平面上有大小相同的A、B两球在同一直_爱下问搜题

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问题不定项选择

不定项选择

如图所示，光滑水平面上有大小相同的A、B两球在同一直线上运动。两球质量关系为m_B=2m_A，规定向右为正方向，A、B两球的动量均为6 kg·m/s，运动中两球发生碰撞，碰撞后A球的动量增量为-4 kg·m/s，则（）

A．左方是A球，碰撞后A、B两球速度大小之比为1∶10

B．左方是A球，碰撞后A、B两球速度大小之比为2∶5

C．右方是A球，碰撞后A、B两球速度大小之比为2∶5

D．右方是A球，碰撞后A、B两球速度大小之比为1∶10

答案

答案：B

多项选择题

关于新生儿低血糖症，叙述中正确的有（）

A.足月儿出生3d内血糖＜1.67mmol/L（30mg/dl）

B.足月儿出生3d后血糖＜3.3mmol/L（60mg/dl）

C.低体重儿3d内血糖＜1.1mmol/L（20mg/dl）

D.低体重儿1周后血糖＜2.2mmol/L（40mg/dl）

E.全血血糖＜2.2mmol/L（40mg/dl）

完形填空

The day that I met my best friend for the first time, I was full of anxiety. I was trying to do some ______ for an important oral exam in the local library, but people kept ______ me. I was getting annoyed and of course, I wasn’t able to ______. Suddenly I heard someone singing behind me. I ______ and glared at the person who was singing. It was a tall girl about the same age as me.
She looked like a sensitive, friendly girl didn’t matter. If anything, it made me even angrier.” How could she be so selfish?” I thought ______.
I picked up my books, glared at her and whispered coldly, “Thanks to your ______, I’ve been unable to study. You’re so ______!”
I left the library in such a hurry, I left the most important textbook ______. when I got home two hours later, I found that textbook gone. I was so ______ that I almost cried. Just then, the phone rang. a gentle voice ______ the speaker as Jenny and asked if I was Jane. After ______ that I was, she said that she had noticed I’d left my book in the library and as my ______ was in it, she’d asked a librarian to get my phone number f. She said that she didn’t live far away and could bring it around for me if I needed it.
I sighed with ______and agreed to meet her at the convenience store down the road. Of course you’ve ______ who Jenny was. She was the girl I had shouted at for singing in the library. When I recognized her in the convenience store, I was filled with ______ and apologized for my ruled behavior I felt so ______, but Jenny just laughed, saying she was glad to see that I’d also left my ______ in the library! I couldn’t help laughing at this and I invited her back to my apartment for a quick cup of tea.
Ever since then we’ve been best friends and we got along really well. To be honest, I trust her more than any one else. I often think how ______ I am. If Jenny hadn’t been a kind person who was willing to ______ my shortcomings, I would ______ have experienced such true friendship.

C．concentrate

A．turned around

B．turned down

D．turned over

D．satisfaction

A．considerate