请通读下面短文，掌握其大意，从每小题所给的四个选项中选出一个最佳答案。
Betty is a nine-year old girl. She always says to her mom, "No, thanks. No 1 for me. But her mom thinks it's good for her to have milk. Milk has calcium (钙) and keeps her 2 .
Today, Betty gets a book from school. Her teacher asks the students to 3 a book about a cat called Casper. Betty loves cats very much, 4 she is very happy to do that. A few minutes later, Betty cries (哭喊), "Oh, dear! Casper can't 5 ."
Later, again she cries "Oh, dear! Casper can't climb a tree!"
Betty's mom walks to her and 6 , "Are you OK, Betty?"
"I'm fine, Mom. It's just that Casper can't walk or climb."
"I'm 7 Casper will be OK. It's 6 o'clock now. Let's have 8 ," says Betty's mom.
After reading the book, Betty goes to her mum and 9 some milk. That evening, Betty has her 10 glass of milk. "Mom, Casper needs Calcium to walk, climb and keep strong, I need it too," says Betty.
