sometimes

occationally

from time to time

now and then

at whiles

on occasion

以上都是“有时候”的意思

例句：

Sometimes defeat is snatched from the jaws of victory.

有时失败是从胜利的口中夺走的。

Occationally， some programs are interesting but most of the time they're rubbish.

偶尔节目很有意思，但大多数情况下他们是垃圾。

You have on occasion surprised people.

你有时使人们感到诧异。