题目

两只杂合黑豚鼠交配，后代出现白豚鼠的原因最可能是什么？杂合黑豚鼠一胎生出4只豚鼠，则出现3 黑1白的可能性为 ( ) A．受精作用时，非等位基因的自由组合；27/64 B．减数分裂时，等位基因的分离；27/256 C．受精作用时，非等位基因的自由组合；27/256 D．减数分裂时，等位基因的分离；27/64 答案：B阅读理解。Peter is a tall boy. He is 1.8 meters tall. He lives in Canada. On Sunday morning he likes to go to see his friend. Her name is Alan. She is a girl. She has a good garden(花园). There are many trees and rose in the garden. They are apple trees oranges trees and other fruit trees. There are lots of fruits on the trees. There are many birds in the garden, too. They are happy. The birds sing in the trees. Peter and Alan listen to the birds and sing songs with them. They draw pictures of birds.It’s lunch-time. They are hungry. They go to a restaurant. Peter would like some dumplings. Alan wants to have a bowl of noodles. They order them for lunch.1. Peter .A. has a girl friend B. is a short boyC. lives in China D. goes to see Alan in the garden2. Here are many in the garden.A. vegetables B. cats and dogsC. fruit and flowers D. children3. Sing in the trees.A. Peter and Alan B. BirdsC. Fruit D. Roses4.Peter and Alan .A. don’t like songs B. don’t like birdsC. like birds D. like new clothes5.They have lunch .A. in school B. In Alan’s homeC. in peter’s home D. in a restaurant