1.in memory of 纪念
例句：
He founded the charity in memory of his late wife.
他兴办那项慈善事业以纪念他已故的妻子。
2.at the mercy of 在……支配下
例句：
The picnic was at the mercy of the weather.
去不去野餐要由天气决定。
3.by mistake 错误地
例句：
Don't board the wrong bus by mistake.
不要上错了汽车。
4.at the moment 现在，此刻
例句：
She's on the telephone at the moment.
她此刻正在打电话。
5.for a moment 片刻，一会儿
例句：
Stop discussing for a moment.
现在请别议论了。