经典途径激活血清补体作用最强的Ig是（） A.IgA B.IgD C.IgE D.I_爱下问搜题

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问题单项选择题 B1型题

经典途径激活血清补体作用最强的Ig是（）

A.IgA

B.IgD

C.IgE

D.IgG

E.IgM

答案

参考答案：E

解析：1.IgG是唯一能通过胎盘的抗体，其Fc段能与SPA结合。2.IgM为五聚体的抗体分子，激活补体的能力比IgG更强，IgM单个分子在结合抗原后即可激活补体。3.原发性巨球蛋白血症是以分泌IgM的浆细胞恶性增殖为病理基础的疾病，其患者血清IgM异常增高。

完形填空

Working Christmas Day
It was unusually quiet in the emergency room on December 25．I was a nurse      that day, sighing about having to work on Christmas．Just then five bodies showed up at my      ，a pale woman and four small children．
“Are you all     ? ” I asked doubtfully．
“Yes．”the woman said     and lowered her head．
But when it came to the     of their problems，things got a little strange．Two of the chlidren had headaches,      weren’t accompanied by the normal symptoms of being ill．Two children had earaches，but only one could tell me which ear was     ．The mother complained of a      but seemed to work to produce it．
“It may be a little while      a doctor sees you．” I explained．
“Take your time；it’s warm here．”She      ．
Whne they were waiting，I checked the chart．They had no      —they were homeless．The waiting room was warm．I looked out at the      by the Christmas tree．The youngest one was saying      to her mother．The oldest one was looking at the Christmas tree．
I went back to the nurses’ station and      the homeless family in the waiting room．The nurses，complaining about the working Christmas，began to feel pity for a family just trying to get      on Christmas．The team went into action，as we do when there’s a      emergency, but this was a Christmas emergency．
We      a simple dinner for our Christmas guests in the hospital cafeteria．They needed     ，so we collected from different departments candies and other things     that could be presents．
As the family walked to the door to leave，the four-year-old came running     , gave me a hug and whispered，” Thanks for being our angel today．”

A．on business

B．descriptions

C．suggestions

填空题

每台PLC至少有一个（），它按PLC的系统程序赋予的功能接收并存贮用户程序和数据，用扫描的方式采集由现场输入装置送来的状态或数据，并存入规定的寄存器中。