问题
单项选择题
与X线吸收衰减系数无关的是（）
A.物质的厚度
B.物质的密度
C.物质的原子序数
D.扫描的时间
E.扫描所采用能量大小
答案
参考答案：D
解析：物质的线性吸收系数与X线的能量、物质的原子序数、厚度、密度有关，而与扫描时间长短无关。
搜题请搜索小程序“爱下问搜题”
与X线吸收衰减系数无关的是（）
A.物质的厚度
B.物质的密度
C.物质的原子序数
D.扫描的时间
E.扫描所采用能量大小
参考答案：D
解析：物质的线性吸收系数与X线的能量、物质的原子序数、厚度、密度有关，而与扫描时间长短无关。
| 完形填空 | ||||
| John loved playing basketball after school. John's parents were anxious about their son because he 1 half of his spare time playing basketball, even though he would soon 2 the college entrance exam (高考). Many evenings, John returned home 3 at the beginning of the new term. His parents told him to concentrate more 4 his studies, but their words went in one 5 and out the other. His parents were so angry that they 6 his basketball. From that day on, John returned home on time but locked 7 in his room. At first, his parents dreamt their son could study hard to enter a top university. But 8 news shattered (破灭) their dream. John's pre-exam test scores were 9 . One night, John's mother looked into his room and 10 him reading a basketball magazine. So John's parents discussed the matter. They 11 to make a deal (约定) with John. If John scored high marks in the following tests, he could get his ball back and 13 once again; if he failed, they would keep the ball 12 he improved. John 14 reading his magazines. He started working hard. He started getting high marks and got his 15 back. The ball stayed with John until he entered a top university. | ||||
|
