1. in 后常接較大的時(shí)間，如：月份，季節(jié)，年, 世紀(jì)等。也有固定搭配in the morning, in the afternoon, in the evening. 

Her bithday is in January, and mine is in the fifth month. 

Most people like going swimming in summer in that area. 

In the 1990s, people liked that song a lot. 

2. on后常接具體的某天或某天的早中晚上。

He always goes fishing on Saturdays and Sundays. 

We have a Spanish lesson on Tuesday afternoon. 

He met an old man who looks like his lost uncle in the park on a cold winter morning. 

3. at常與具體時(shí)刻連用。還有常見的固定搭配at dawn, at noon, at night, at midnight. 

She gets up at 6:20, and then she exercises for half an hour. 

4. for 后常跟一段時(shí)間

I often play soccer with my friends  for an hour after school. 

He has been living here for 5 years.