2. 外语
  3. The term "virus" is derived from the Latin word for position, or slime. It was originally applied to the noxious stench emanatin

The term "virus" is derived from the Latin word for position, or slime. It was originally applied to the noxious stench emanatin

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问题     The term "virus" is derived from the Latin word for
position, or slime. It was originally applied to the noxious
stench emanating from swamps that was thought to cause a
variety of disease in the centuries before microbes were             S1.______
discovered and specifically linked to illness. But it was            S2.______
until almost the end of the nineteenth century that a true
virus was proven to be the reason of a disease.                      S3.______
    The nature of viruses made them impossible to detect
for many years, even after bacteria had been discovered and
studied. Not only are viruses too small to be seen with a
light microscope, they also cannot be detected through their         S4.______
biological activity, except as it occurs in conjunction with
other organisms. In fact, viruses show no traces of biological
activity by themselves. Unlike bacteria, they are not living
agents in the strictest way. Viruses are very simple pieces          S5.______
of organic material composing only of nucleic acid, either           S6.______
DNA or RNA, enclosed with a coat of protein made up of               S7.______
simple structural units. (Some viruses also contain
carbohydrates and lipid.) They are parasites require                 S8.______
human, animal, or plant cells to live. The virus replicates
by attaching to a cell and inject its nucleic acid; once             S9.______
inside the cell, the DNA or RNA that contains the virus’
genetic information takes on the cell’s biological machinery,        S10.______
and the cell begins to manufacture virtual proteins rather
than its own.
选项
答案disease→diseases
解析 本题考查名词单复数用法。a variety of+名词复数，指“各种各样的……”。
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