According to the meaning of the sentence and the prompts to complete the sentence.
1.Wearing a smile on your face not only helps you make friends but also makes you ____(feel) better.
2.Hurry up,or we can't ____ (arrive at) the railway station on time.
3.I'm looking forward to ____ (meet) my old friend,Jim,this Sunday.
4.It is necessary for us ____ (understand) the importance of health care.