306　o'clock和hour

1　o'clock 是of clock的缩写，表示“……时……点钟”，指钟表上的某一时刻，时间的某一点，用于正点，“几点几分”不可用o'clock。

It's six o'clock in the morning. 时间是早上6点钟。

A： What time is it? 几点了 ?

B： It's ten (o'clock). 10点了 。（o'clock也可省略 ）

It's ten past five.（正）5点10分 。

It's ten past five o'clock .（误）

2　“在几点”要用at ，如：“在4点钟”是at four o'clock，“在9点钟”是at nine o'clock。

She came at three o'clock and left at seven o'clock . 她3点钟来的，7点钟离开的。

3　hour 意为“小时”，是指时间的长度单位；“1个小时，几个小时”要用hour ，为one hour， several hours，不可用o'clock。

I saw him an hour ago. 我在一个小时前见到他的。

How many hours are there in a day? 一天有多少个小时？

He has waited for you for three hours . （正）他已经等你3个小时了 。

He has waited for you for three o'clocks . （误）