when

• Be particularly careful when driving at night .
  晚上开车要特别小心。
• The horse perked up its head when i shouted .
  我吆喝时那马扬起了头。
• There are nights when he goes off by himself .
  晚上他有时会只身外出。
• Do you wish when you see a shooting star ?
  你看见流星时提出愿望吗？
• He was out of work when the factory closed .
  他在工厂倒闭后失业了。
• He had scarcely escaped when he was recaptured ...
  他一逃就被逮住了。
• When the car is in gear it will move .
  汽车挂上档以后，就可以开动了。
• I 'm always nervous when i make a speech .
  在发言时我总是感到紧张。
• When she spoke, her voice was frosty .
  当她说话时，她的声音是冰冷的。
• I got into a real flap when i lost my keys .
  我丢了钥匙，心里发慌。