问题
选择题
人工建立一个数量足够大的果蝇实验群体，雌雄个体数量相当且均为杂合子。已知某隐性基因纯合致死，预测该隐性基因频率的变化曲线应该是(纵坐标表示该隐性基因频率)[ ]
A．
B．
C．
D．
答案
答案：C
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人工建立一个数量足够大的果蝇实验群体，雌雄个体数量相当且均为杂合子。已知某隐性基因纯合致死，预测该隐性基因频率的变化曲线应该是(纵坐标表示该隐性基因频率)[ ]
A．
B．
C．
D．
答案：C
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| This week we asked students at New Star High School about the best ways to learn more English. Many said they learned by 1 English. Some students had more specific 2 . Lillian Li, for example, said the best way to learn new words was 3 reading English magazines. She said that memorizing the words of pop songs also 4 a little. When we asked about studying grammar, she said, "I 5 study grammar. It's too boring." Wei Ming feels differently. He's been leaning English for six years and really loves it. He 6 studying grammar is a great way to learn a 7 . He also thinks that watching English movies 8 a bad way because he can watch the actor 9 the words. Sometimes, however, he finds watching movies frustrating 10 the people speak too quickly. Liu Chang said that 11 the English club at school was the best way to improve her English. Students get lots of practice and they also have fun. She added that having conversations with friends was not helpful at all. "We get 12 about something and then end up speaking in Chinese," she said. | ||||
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