题目

根据括号内所给单词的适当形式填空（5分） 1. Look! She ______(hiccup). 2. Tom_______(bear) in 2001. 3. Who is ______(young) in your family. 4. The apple is high for me ______(reach). 5. My sister ______(become) a worker 5 years ago.  答案：1. is hiccupping 2. was born 3. the youngest 4. to reach 5. became某种群中，AA的个体占25%，Aa的个体占50%，aa的个体占25%。若种群中aa的个体无繁殖能力，则该种群的雌雄个体自由交配产生的子代中AA∶Aa∶aa的比值和分别自交产生的子代中AA∶Aa∶aa的比值分别是 A．5∶2∶3 ；1∶2∶0                        B．4∶4∶1 ；1∶2∶0 C．4∶4∶1 ；3∶2∶1                        D．5∶2∶3 ；3∶2∶1