问题
单项选择题
关于公式Kx-e-μd.说法错误的是（）.
A.表示X线透过物质后的分布差异
B.μ为吸收系数
C.d为X线传播的距离
D.Kx与物质的特性无关
E.μ随管电压升高而降低
答案
参考答案：D
解析：物质不同，则μ不同，Kx就不同。
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关于公式Kx-e-μd.说法错误的是（）.
A.表示X线透过物质后的分布差异
B.μ为吸收系数
C.d为X线传播的距离
D.Kx与物质的特性无关
E.μ随管电压升高而降低
参考答案：D
解析：物质不同，则μ不同，Kx就不同。
Passage Two
| Jee Hock and Meng Kim were very good friends. Jee Hock could not see. He was blind. Meng Kim could not walk. He was lame. They lived in a village near a forest. Everyone in the village was going to a rich man’s dinner on the other side of the forest. Jee Hock and Meng Kim were anxious to attend the dinner too. Blind Jee Hock thought of a plan. He would carry Meng Kim. The lame man could tell him the way. Meng Kim said that the plan was a good one. On the way through the forest, Meng Kim saw a tiger. He did not tell Jee Hock about it. Instead, he quietly asked Jee Hock to carry him to the nearest tree. Upon reaching an over banging branch, Meng Kim quickly hauled himself up. Then the tiger roared. Jee Hock at once knew a tiger was near. He lay down quietly. The tiger came to him and sniffed his body. The tiger’s whiskers touched Jee Hook’s nose. At once Jee Hock sneezed, "Ah Choooooo!" The tiger was afraid and ran away. Then Meng Kim came down from the tree. He asked Jee Hock about the tiger. Jee Hock said that the tiger had told him to choose his friends wisely. |
Jee Hock knew the tiger was near. He ______.
A．went to sleep
B．cried
C．sat down and waited
D．lay down quietly