关于声的知识，下列说法错误的是（   ）

—        dog is this?—It's mine.

化简sin（α﹣ $\frac{\pi }{2}$ ）•tan（π﹣α）=____．

   Linda is a 15-year –old American girl. She is outgoing and likes making friends. Her parents are very   1 .They have no tome to stay with Linda,  2she spends a lot of time on the Internet(网络) every day. She likes  3    with other people on QQ and her QQ name is Lily.
   Last year, Linda got to know a young man on the Internet.  4 name is Mike. Mike is 18 years old. He lives  5  Toronto, Canada. He is very friendly and 6
   He likes to tell jokes and makes Linda happy. Linda talked with him on QQ for long hours every night. A few days later, Mike posted a 7 of himself(他自己) to Linda. He is 8 and good-looking in the photo. Linda likes him very much and they become good friends.
   Last month, Linda’s parents went to Toronto for a meeting (会议). Linda wanted to visit his friend Mike. She asked her parents to  9her there. When Linda arrived at Mike’s house, she found her 10was only a nine-year-old boy .He wasn’t that tall man in the photo. How surprised Linda was!

小明在学习二次根式后，发现一些含根号的式子可以写成另一个式子的平方，如：3+2 $\sqrt{2}$ =（1+ $\sqrt{2}$ ）²，善于思考的小明进行了以下探索：

设a+b $\sqrt{2}$ =（m+n $\sqrt{2}$ ）²（其中a、b、m、n均为整数），则有a+b $\sqrt{2}$ =m²+2n²+2mn $\sqrt{2}$ ，∴a=m²+2n²，b=2mn，这样小明就找到了一种把部分a+b $\sqrt{2}$ 的式子化为平方式的方法．

请我仿照小明的方法探索并解决下列问题：