- 1.
[疑问副词] 什么时候，何时 -
• When is your birthday? 你哪一天生日？ -
• When can you come here? 你什么时候能来这里？ - 2.
[关系副词] 当…的时候 -
• I often think of the happy days when I was in France. 我经常想起在法国时的那段快乐日子。 - 3.
[关系副词] 就在那时候 -
• I was about to leave the office when the telephone rang. 我正要离开办公室时电话响了。 - 4.
…的时候 -
• The morning is when I'm busiest. 早上是我最忙的时候。