at times:
有时；不时
[例句]
The tide is,at times,very high.
潮水有时涨得很高.
I like Bob but he's very annoying at times.
我喜欢鲍勃,但是他有时也很烦人.
at a time
作“一次,每次”讲,常用于“数词+at a time”的结构中.例如：
Enter two at a time.
每次进来两人.
at time 偶而
1.One expects healthy children to be mischievous at times.
健康的孩子有时很调皮,这是意料之中的.