重点讲解：
1. depend on 取决(于)；有赖(于)；
The cooking time needed depends on the size of the potato.
所需的烹饪时间取决于土豆的大小Wm=evR_kkN+aAV~p。
2. shut off 关闭；关上；使停止运转；
They pulled over and shut off the engine.
他们靠边停车熄火gsJ*bCu65T-MVE。
3. burn the candle at both ends 一根蜡烛两头烧；起早摸黑地干；过度耗费精力；
You can't burn the candle at both ends.
你不能过度耗费精力FjV&+HYG%0。
4. trade sth. for sth. 用…进行交换；互相交换；
They traded land for goods and money.
他们用土地换取了货物与金钱.qeHcRl*]RjI9G)&4rX。