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【单选题】
医院感染的发生必须具备的三个基本条件是A.
感染源、空气传播、接触传播
B.
感染源、原位菌群失调、抵抗力下降
C.
感染源、传播途径、易感宿主
D.
感染源、接触传播、抵抗力下降
E.
感染源、细菌移位、易感生态环境
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【简答题】一对减速齿轮传动,若保持两齿轮分度圆的直径不变,而减少齿数和增大模数时,其 齿面接触应力将 。
【简答题】阅读理解 So you're between the ages of 13 and 24. What makes you happy? A worried, weary parent might imagine the answer to sound something like this: , drugs, a little rock 'n' roll (摇滚乐). Maybe some ...
【单选题】What makes traditional surveys unscientific according to the second paragraph?
A.
The sampling is not made strictly randomly.
B.
The interview has to be conducted face-to-face.
C.
Improper questions are often included in a survey.
D.
Selection of respondents is often a matter of personal decision.
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