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问题 解答题

有一块三角形的小麦试验田，底250米，高68米，共收小麦11900千克，平均每平方米收小麦多少千克？

答案

11900÷（250×68÷2），

=11900÷8500，

=1.4（千克）；

答：平均每平方米收小麦1.4千克．

单项选择题

A child is sent to the school nurse because, according to his teacher, he’s constantly scratching his head. When the nurse assesses his hair and scalp, she finds evidence of lice. What did she probably see

A. Flaking of the scalp with pink, irritated skin exposed.
B. Small white spots that adhere to the hair shaft, close to the scalp.
C. Scaly, circumscribed patches on the scalp, with mild alopecia in these areas.
D. Multiple tiny pustules on the scalp with no abnormal findings on the hair shafts.
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单项选择题 A1/A2型题

原子核的自旋可形成电流环路，从而产生具有一定大小和方向的磁化矢量，这是因为原子核内（）

A.中子带有正电荷

B.质子带有正电荷

C.电子带有负电荷

D.中子带有负电荷

E.质子带有负电荷
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