1. 时间前的at/in/on

1. 具体到某天用on

• On January 25th
• On January 25, 2010

2. 具体到年或者月用In

• In 2010
• In January
• In January 2010

3. 具体到几点用at

• I get up at six in the morning.
• In January 2010, 25th, at 6:00 a.m

4. 一些固定搭配

• in the morning/afternoon/evening
• at noon/night
• on the weekend
• on school days 在上学日
• late at night 在深夜

2. assure 和 ensure 的区别

• I want to assure you that nothing will go wrong tomorrow．
  我想向你保证，明天不会出错。assure是“向某人保证”(make someone confident)的意思
• I want to ensure that nothing will go wrong tomorrow．
  我想确保明天不会出错。ensure是“确定”(make certain)的意思

3. might 和 may

1. may 可以放在句首也可以放在句中
2. 而might 要放在句中不能放在句首
3. might 在虚拟语气时用的较多
4. 再有就是 might 在作为 may 的过去试时候用