问题
单项选择题
杂交育种后代的选育方法中，集团混合选择法是在（）。
A.早代不选，F4-F8代才开始选株建系
B.分离世代每株只留一粒种子混合播种，F4-F8代才选取株建系
C.分离世代选优株混收混播，F4-F8代才选取株建系
D.在第一分离世代按成熟期，株高等相近类型归类，混收混播，F4-F8代才选株建系
答案
参考答案：D
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杂交育种后代的选育方法中，集团混合选择法是在（）。
A.早代不选，F4-F8代才开始选株建系
B.分离世代每株只留一粒种子混合播种，F4-F8代才选取株建系
C.分离世代选优株混收混播，F4-F8代才选取株建系
D.在第一分离世代按成熟期，株高等相近类型归类，混收混播，F4-F8代才选株建系
参考答案：D
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| 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 12 once again; if he failed, they would keep the ball 13 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. | ||||
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