题目

在数列{an}中，a1=1,an+1=an2-1,则a1+a2+a3+a4+a5等于（    ）A.-1                B.1              C.0              D.2 答案：解析：∵a1=1,∴a2=a12-1=0,a3=a22-1=-1,a4=a32-1=0,a5=a42-1=-1.∴a1+a2+a3+a4+a5=-1.答案：AThis is a room in Kate’s house. There is a big bed, a table, a computer and some chairs in it. There’s a glass and some books on the table. There is a picture on the wall. Kate is in the room. She is looking at the picture. Her father and mother are in the school. They work hard.1.Is there only one room in Kate’s house?A. Yes, there is. B. There is a bed.C. There is a computer. D. I don’t know.2.What’s in the room?A. Only a bed.B. Only a table.C. Only some chairs.D. A bed, a table, a computer and some chairs.3.Is there anything on the table?A. Yes, there is. B. No, there isn’t.C. Some books. D. A glass.4.Who is at home?A. Kate’s father. B. Kate’s mother.C. Kate s brother. D. Kate.5.Kate’s father and mother are ________.A. teachers B. studentsC. friends D. at home