2. 职称英语
  3. Throughout history man has had to accept the fact that all living things mus

Throughout history man has had to accept the fact that all living things mus

游客2024-02-29  40
问题     Throughout history man has had to accept the fact that all living things must die, but people now live longer than they 【C1】______. Yet, all living things still show the【C2】______of aging, which will eventually【C3】______death.
    Aging is not a disease, but as a person passes maturity, the cells of the body and the【C4】______they form do not function as well as they【C5】______in childhood and adolescence (青春期), The body provides less【C6】______against disease and is more inclined【C7】______accident.
    A number of related causes may【C8】______aging. Some cells of the body have a fairly long life, but they are not【C9】______when they die. As a person ages,【C10】______of brain cells and muscle cells decreases.【C11】______body cells die and are replaced by new cells. In an aging person the【C12】______cells may not be as viable (能生存的)or as capable【C13】______growth as those of a young person.
    Another【C14】______in aging may be changes within the cells【C15】______. Some of the protein chemicals in cells are known【C16】______with age and become less elastic. This is why the skin of the old people wrinkles and【C17】______. This is also the reason old people【C18】______in height. There may be other more important chemical changes in the cells. Some complex cell chemicals, such as DNA and RNA, store and【C19】______information that the cells need. Aging may affect this【C20】______and change the information-carrying molecules so that they do not transmit the information as well. [br] 【C15】
选项 A、for themselves
B、by themselves
C、themselves
D、on their own
答案 C
解析
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