open a crossing

例句：

1. 1. The door was open when I arrived.
   我到达时门是开着的。
2. 2. She opened the window to let fresh air in.
   她打开了窗户，让新鲜空气进来。
3. 3. The scientist opened the box to reveal its contents.
   科学家打开了盒子，揭示了里面的内容。