阅读下面短文，从短文后各题所给的四个选项（A、B、C和D）中选出可以填入空白处的最佳选项。
AMERICA'S first daughters, Malia and Sasha, are excited about getting a pet dog. But their father, President Obama, has told the girls they have to pick up the poop(狗粪)1the grass. It's true. Keeping a dog 2 lots of other work besides(除…之外) picking up the poop. For example, you'd better know3the dog goes to bed and how it lives happily. It means you have to know the animals'4 and be ready.
Li Hui, 15, of Beijing, once kept a rabbit and some goldfish.5 all of them died. "My rabbit ate the wrong food," said Li. "My6 died because they ate too much!"
Xiao Ting, 15, of Shanghai, wanted to keep a dog a year ago. She got food and a new doghouse ready to 7 the dog, but she only kept the dog for one day. "I 8 thought a dog could be so active. It wouldn't stop barking(吠). My father had to walk9 at 3 o'clock in the morning!"
"You'd better think it is like your10." said Liu Yining, a11 Beijinger. She is a (an)12 pet keeper. Her family has kept a dog named Pipi for three years.13 Pipi first came to Liu's home, it made her house dirty everywhere. It took a long time to teach Pipi to go to the toilet. She talks and plays with Pipi a lot. She really 14Pipi.
15 a pet means you have to be patient and caring.
