问题 单项选择题

人体对病原菌具有一定的防御功能,下列叙述错误的是()。

A.唾液中的溶菌酶可杀死病原菌

B.口腔黏膜对病原菌具有一定的屏障作用

C.吞噬细胞对多种病原菌具有吞噬作用

D.T细胞不参与体液免疫过程

答案

参考答案:D

解析:溶菌酶可以杀死病菌,A正确。皮肤和黏膜是人体的第一道防线,B正确。吞噬细胞可以吞噬多种病原菌,C正确。体液免疫过程中,T细胞分泌淋巴因子,刺激B细胞分化为浆细胞,D错误。

选择题
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In times of economic crisis. Americans turn to their families for support. If the Great Depression is any guide, we may see a drop in our skyhigh divorce rate. But this won't necessarily represent. an increase in happy marriages. In the long run, the Depression weakened American families, and the current crisis will probably do the same.

  We tend to think of the Depression as a time when families pulled together to survive huge job losses, By 1932. when nearly one-quarter of the workforce was unemployed, the divorce rate had declined by around 25% from 1929 But this doesn't mean people were suddenly happier with their marriages. Rather, with incomes decreasing and insecure jobs, unhappy couples often couldn't afford to divorce. They feared neither spouse could manage alone.

  Today, given the job losses of the past year, fewer unhappy couples will risk starting separate households, Furthermore, the housing market meltdown will make it more difficult for them to finance their separations by selling their homes.

  After financial disasters family members also tend to do whatever they can to help each other and their communities, A 1940 book. The Unemployed Man and His Family, described a family in which the husband initially reacted to losing his job "with tireless search for work."He was always active, looking for odd jobs to do.

  The problem is that such an impulse is hard to sustain Across the country, many similar families were unable to maintain the initial boost in morale(士气). For some, the hardships of life without steady work eventually overwhelmed their attempts to keep their families together. The divorce rate rose again during the rest of the decade as the recovery took hold.

  Millions of American families may now be in the initial stage of their responses to the current crisis, working together and supporting one another through the early months of unemployment.

  Today's economic crisis could well generate a similar number of couples whose relationships have been irreparably(无法弥补地)ruined. So it's only when the economy is healthy again that we'll begin to see just how many broken families have been created.

小题1:In the initial stage, the current economic crisis is likely to __________.

A.tear many troubled families apart

B.contribute to enduring family ties

C.bring about a drop in the divorce rate

D.cause a lot of conflicts in the family小题2:In the Great Depression many unhappy couples close to stick together because

A.starting a new family would be hard

B.they expected things would turn better

C.they wanted to better protect their kids

D.living separately would be too costly小题3:In addition to job losses. What stands in the way of unhappy couples getting a divorce?

A.Mounting family debts

B.A sense of insecurity

C.Difficulty in getting a loan

D.Falling housing prices小题4:What will the current economic crisis eventually do to some married couples?

A.It will force them to pull their efforts together

B.It will undermine their mutual understanding

C.It will help strengthen their emotional bonds

D.It will irreparably damage their relationship小题5:What can be inferred from the last paragraph?

A.The economic recovery will see a higher divorce rate

B.Few couples can stand the test of economic hardships

C.A stable family is the best protection against poverty.

D.Money is the foundation of many a happy marriage