It's Sunday afternoon. Michael's family have a picnic under (在……下面) a big tree. The woman in a blue T-shirt and white pants is Michael's mother. ⑴She is thirty-two. She is a teacher in No. 2 high School. She is cooking now. The man with a guitar is Michael's father. He is thirty-four years old. ⑵He teaches in the same school as Michael's mother. He is a teacher. Michael's little sister likes singing, but she isn't singing now. ⑶“为什么不和我一起去放风筝呢？”Michael问他的小妹妹。⑷Then she flies a kite with her brother. What a happy family!

一个两位数x，还有一个两位数y，若把两位数x放在y前面，组成一个四位数，则这个四位数为（　　）