(1) perhaps表示“或许”，但有疑问，不肯定。

• Perhaps , he will come.
  或许他会来。

 (2) likely用作副词时，表示“很可能”，多与most或very连用，较perhaps肯定。

• Most likely he'll go there along with his family.
  很可能他将与家人一起去那里。
• I shall very likely be here again several days later.
  几天后我很可能再来这里。

 (3) as likely as not意为“多半会，可能会”，用于一次性的场合。

• So long as you keep on, you'll succeed as likely as not .
  只要你坚持，你多半就会成功。

 (4) possibly意思为“有可能”，但可能性不大。

• I may possibly go to the meeting.
  我可能去参加会议。

 (5) probably意思是“很可能，十有八九”，等于most likely。

• I'll probably go to the meeting next week.
  我下周可能去参加会议。

 (6) maybe用于口语中表示“可能，也许”，语气上近似possibly, perhaps。

• Maybe we'll see you next week.
  我们可能下周去看你。
• I think maybe they don't want him, he is so cross.
  我想，可能他们不想要他，他脾气不好。