根据句子意思及所给的词首字母或汉语提示，完成下列单词。 
 Both of them are nice and cheap. I really don't know which one I should c____.
  F____the doctor's advice, and you will get better soon.
 Our Chinese teacher wants us to write a d____ every day to improve our writing.
 That baby has only three ____(牙齿) . He can't eat that apple.
 Tan Jiexi's song “Run, Run, Run” is very ____(流行的) among young people.