根据所给首字母或汉语提示完成单词。
小题1:The old s is, "Who laughs last, who laughs best!"
小题2:I had a toothache, so I must go to see the (牙医).
小题3:It's hard to (选择) the best answer to the question.
小题4:He saw some (老鼠)in the street yesterday.
小题5:My brother Jack is more (外向的)than me.