Use:Can, Could, Be able to:
1...................he understand what you were talking about?
2.My sister...............play tennis now.
3.I.................walk when I was less than a year old.
4.(Polite)...................you tell me what time it is, please?
5.My grandfather ...................walk without any help last night.
6.I would like to...................play the piano.
7.How long have you....................to drive?
8.I'll....................help you later.
9.Can you help me? I ....................never understand this.
10.Will Man..................live forever one day?