一、Be动词练习题:1、I a student.2、She a nurse.3、He a doctor.4、It a dog.5、Mary my sister.6、They students.7、I your friend.8、My mother is a policeman.9、You a pupil.10、we good friends.11、This my book.12、That your pen.13、these our house.14、Those your books.15、Mary and Lucy sisters.16、You teachers.17、He from China.18、She my mother.二、把下列句子变成否定句。1、