问题
选择题
下列哪一项能正确表示正常女性体细胞及卵细胞中的全部染色体
A．44+XX和22+X
B．46+XX和23+X
C．44+XX和X
D．46+XX和X
答案
答案：A
人的23对染色体中，有22对常染色体和1对性染色体，女性的一对性染色体是XX，所以女性体细胞中的染色体可以表示为44+XX，卵细胞内染色体为：22条常染色体+X。
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下列哪一项能正确表示正常女性体细胞及卵细胞中的全部染色体
A．44+XX和22+X
B．46+XX和23+X
C．44+XX和X
D．46+XX和X
答案：A
人的23对染色体中，有22对常染色体和1对性染色体，女性的一对性染色体是XX，所以女性体细胞中的染色体可以表示为44+XX，卵细胞内染色体为：22条常染色体+X。
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| Mr. Green works in an office in Chicago. 1 Saturday, he went to the office to do some work. When he got on the elevator, it stopped between the 2 . Mr. Green could not get out of the elevator. He started to 3 , but no one 4 him. Then Mr. Green remembered that it was a holiday in America. No one was going to come to work 5 Tuesday. There was 6 for him to do. He had to wait. With nothing to eat 7 drink, Mr. Green slept for most of the time. Early Tuesday morning, his 8 came to work and found the elevator was not working. When the elevator was 9 , Mr. Green came out. He was cold, weak, and tired. He had been in the elevator for about sixty-four 10 ! Now Mr. Green says, "I will only use elevators if they have a telephone in them."
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