介詞at，in，on都可用來表示時(shí)間，只是用法不同。現(xiàn)將這三個(gè)介詞的用法歸納如下：

一、at的時(shí)間表達(dá)法

用于表示在三餐或中午、晚上。

1．What did your mother say at breakfast ／lunch ／supper time？

2．We heard a girl singing in the next room at noon ／night．

用于表示時(shí)間上的某一點(diǎn)或某一時(shí)刻。如：

3．What were you doing at this time yesterday？

4.We often start classes at eight o’clock in the morning．

用于表示節(jié)氣、年齡。如：

5.I often receive presents at Spring Festival．

6.Jim began to play the piano at the age of seven．

二、in的時(shí)間表達(dá)法

用于表示非特指的早晨、上／下午、夜晚。

1．I often get up before 6 o’clock in the morning．

2．We like watching TV in the evening．

用于表示在一段時(shí)間內(nèi)。如：

3.Mother will be back in a few days．

4.It would strike twelve in twenty minutes’ time.

用于表示月份、季節(jié)、年、世紀(jì)等。如：

5.Everything begins to grow in spring．

6.The Olympic Games will be held in Beijing in 2008．

三、on的時(shí)間表達(dá)法

用于表示在具體某天或某一特定日子的上午、下午或晚上。

1．I often do my homework on Saturday afternoon．

2.My grandfather died in the mountain on a cold winter afternoon．

用于表示節(jié)日的名詞前。如：

3．Australians often go to church on Christmas Day．

4.Chinese visit their relatives and friends on New Year’s Day．

四、含有early morning，late afternoon之類的詞語(yǔ)時(shí)，通常用in，不用on。

1.in the early morning of 21st，March；

2.in the late afternoon of 15th，September

五、由last，next，this，that，these，those等構(gòu)成的表示時(shí)間的短語(yǔ)前面，通常不用介詞。yesterday，today，tomorrow，tonight等詞前面通常也不用介詞。

1.I bought a Chinese-English dictionary this morning．

2．We traveled to Beijing last summer．