阅读理解
Hello, I'm Sam. I'm from England. Now I am in Beijing with my family. I've got a pet dog. It's lovely and nice.
Tomorrow is Sunday. My sister Amy is going to have a birthday party. Now I'm making a card for her. Dad is buying things at the supermarket. Mum is making a cake for her. What can my pet dog do for Amy? Oh, it can sing and dance for her!
在区间
内单调递增，则
可以是（ ）