题目

果蝇（2N=8）的某一个精原细胞进行减数分裂时发生了一次异常，现分别检测了其分裂进行至T1、T2、T3时期的三个细胞中染色体、DNA、染色单体的数量，结果如图。相关叙述错误的是（ ）A. “交叉互换”的现象可能出现在T1时期B. 最终形成的4个精子中染色体数分别为3、3、5、5C. T2时期对应的这个细胞可能仍含有等位基因D. T3时期对应的这个细胞中Y染色体的数量可能为0、1、2 阅读理解 　　We provide summer English courses and you will enjoy learning about American culture and improve your English．The courses last for 4 weeks．They start at the beginning of July and August．Our teachers are very experienced．They teach English classes for 4 hours a day．You can choose between small groups of 2 or 3,or larger groups of up to15．We provide weekly tests to see the progress you're making with your language skills．We also provide books and other materials． 　　As well as learning English,we want you to experience life in the USA．You live with an American family and take part in American life．You have meals with them and do some activities with them,too．This is the most interesting part of the course．Many families create friendships with the students．Of courses,if you prefer,we can arrange hotel accommodation． 　　Of course,you can do many things in Los Angeles．Every day we have activities after class．You can choose to take trips to Hollywood,Disneyland or the famous beaches around LA．You can also go to various shopping centres,sports centres,movies and concerts．There are also weekend visits organized to San Francisco and other places of interest in California． 　　Well,if you're interested,please fill in our application form where you will also find our list of prices．The courses must be paid for one month before it begins． (1) How long do the English courses last? [　　] A． 4 days． B． 2 weeks． C． 3 weeks． D． 4 weeks． (2) Why do organizers(组织者)advise students to live with American families? [　　] A． Students are not rich enough to live in hotels． B． Students can have meals with American families． C． Students can experience life in the USA． D． Students can teach Americans how to cook Chinese food． (3) What's the title of paragraph 3? [　　] A． Teaching B． Accommodation and Food C． Sightseeing and Other Activities D． The Famous Beaches Around LA (4) What's the passage about? [　　] A． A description of an English book． B． A description of an English course． C． A description of life in Los Angeles． D． A description of weekend visits to San Francisco．