有三个粒子a、b、c(不计重力)以相同的速度垂直射入匀强磁场中,它们的运动轨迹如

题型:实验题

问题:

有三个粒子a、b、c(不计重力)以相同的速度垂直射入匀强磁场中,它们的运动轨迹如图所示,其中b粒子做直线运动,则a粒子带____________电,b粒子____________,c粒子带_______________电.

考点:磁场对运动电荷的作用:洛伦兹力、左手定则
题型:实验题

小强的妈妈要将2.5千克香油分装在一些玻璃瓶中,每瓶最多装0.4千克,需准备6个瓶.______.

题型:实验题

患者停经40天,尿妊娠试验阳性,恶心呕吐3天,头晕厌食,食入即吐。首先应考虑的诊断是()

A.胞阻

B.子满

C.转胞

D.恶阻

E.子气

题型:实验题

当个人取得的月收入为( )元时,作为劳务报酬所得的税负与作为工资、薪金所得课税的税负相等。

A.15375

B.17375

C.19375

D.21375

题型:实验题

乙脑特异性IgM抗体具有如下特征()

A.一般在起病后3~4天出现,脑脊液中最早在病程第2天即可检测到

B.IgM抗体在2周达高峰

C.轻、中型患者检出率高

D.重型及极重型患者检出率最高

E.不能作早期诊断试验

题型:实验题

(A)

Linda Evans was my best friend—like the sister I never had. We did everything together: piano lessons, movies, swimming, and horseback riding.

When I was 13, my family moved away. Linda and I kept in touch through letters, and we saw each other on special time—like my wedding and Linda’s. Soon we were busy with children and moving to new homes, and we wrote less often. One day a card that I sent came back, stamped "Address Unknown." I had no idea how to find Linda.

Over the years, I missed Linda very much. I wanted to share happiness of my children and then grandchildren. And I needed to share my sadness when my brother and then mother died. There was an empty place in my heart that only a friend like Linda could fill.

One day I was reading a newspaper when I noticed a photo of a young woman who looked very much like Linda and whose last name was Wagman—Linda’s married name. "There must be thousands of Wagmans," I thought, but I still wrote to her.

She called as soon as she got my letter. "Mrs. Tobin!" she said excitedly, "Linda Evans Wagman is my mother."

Minutes later I heard a voice that I knew very much, even after 40 years, laughed and cried and caught up on each other’s lives. Now the empty place in my heart is filled. And there’s one thing that Linda and I know for sure: We won’t lose each other again!

There was an empty place in the writer’s heart because she()

A.was in trouble

B.didn’t know Linda’s address

C.received the card that she sent

D.didn’t have a friend like Linda to share her happiness or sadness

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