题目内容
（请给出正确答案）
The rise in skin cancers among young people might result from ______.
A．spending too much time on vacations
B．going to the tanning gatherings too much
C．exposed too little to the sun
D．doing too many exercises
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更多“The rise in skin cancers among…”相关的问题
A、Asians
B、Non-Hispanic Whites
C、Hispanics
D、Blacks
A、Balance the topic sentence.
B、Introduce yourself.
C、State your topic sentence clearly.
D、Give a reasonable opinion.
How does Organisms Ward off Invaders
The livelihood of each species in the vast and intricate assemblage of living things depends on the existence of other organisms．This interdependence is sometimes subtle，some times obvious．Perhaps the most straightforward dependence of one species on another occurs with parasites，organisms that live on or in other living things and derive nutrients directly from them．The parasitic way of life is widespread．A multitude of microorganisms(including viruses and bacteria，and an army of invertebrates or creatures lacking a spinal column(including crustaceans，insects，and many different types of worms)make their livings directly at the expense of other creatures．In the face of this onslaught，living things have evolved a variety of defense mechanisms for protecting their bodies from invasion by other organisms．
Certain fungi and even some kinds of bacteria create substances known as antibiotics into their external environment．These substances are capable of killing or inhibiting the growth of various kinds of bacteria that also occupy the area，thereby eliminating or reducing the competition for nutrients．The same principle is used in defense against invaders in other groups of organisms．For example，when attacked by disease--causing fungi or bacteria，many kinds of plants produce chemicals that help to ward off the invaders．
Members of the animal kingdom have developed a variety of defense mechanisms for dealing with parasites．Although these mechanisms vary considerably，all major groups of animals are capable of detecting and reacting to the presence of“foreign”cells．In fact，throughout the animal kingdom from sponges to certain types of wornls shellfish，and all vertebrates(creatures possessing spinal column)
there is evidence that transplants of cells or fragments of tissues into an animal are accepted only if they come from genetically compatible or closely related individuals．
The ability to distinguish between“self”and“non-self”，while present in all animals，is most efficient among vertebrates，which have developed an immune system as their defense mechanism．The immune system recognizes and takes action against foreign invaders and transplanted tissues that are treated as foreign cells．
What does the passage mainly discuss？ 查看材料
A.How parasites reproduce
B.How organisms react to invaders
C.How antibiotics work to cure disease
D.How the immune system of vertebrates developed
A、I'm afraid I can't go to your party.
B、Sure, I'd love to.
C、Maybe next time.
D、Yes. It's very kind of you.
A．嗨，我是迈克。我现在不在办公室里，我在接电话。请你把你地址留下，我会尽快登门拜访的。
B．嗨，我是迈克。我现在不是不在办公室里就是在接电话。请你留言，我会尽快回话。
C．嗨，我是迈克。我现在不是不在办公室，就是在电话问。请你留言，我会马上给你打电话。
D．嗨，我是迈克。我现在不在办公室。我在打电话。请你把你地址留下，我会尽快打电话给你。
A．在学校里，我苦恼的是学习困难， 因为我老想着身体好了才能学习好。
B．我的学习成绩正受到影响， 因为我老想着的是自己的健康状况而不是我的学习。
C．在学校里，我功课不好，很苦恼， 因为我老是考虑自己的健康状况会影响我的学习。
D．我的学习成绩一直在下降， 因为我老想着的是自己的健康状况而不是学习。
A．The best method of selecting staff is to interview job applicants.
B．The results of an interview will often come out soon after the interview.
C．It takes longer to find out the results of an interview for a vital post.
D．If the interviewer is clear as to what he or she wants to achieve, he/she will achieve it.
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