重点讲解：
1. run into 意外碰到；
Sometimes you'll run into people who cannot wait to pour their hearts out to you.
有时你会碰到迫不及待向你倾诉心声的人c98zRG2POs。
2. switch on 打开，开启(电灯等)；
He didn't bother to switch on the light.
他懒得去开灯A(3oOR;1JFS2。
3. switch off 关掉，关上(电灯等)；
She switched off the coffee-machine.
她关掉了咖啡机Y=o05FK[ZjJY。
4. build up （使）积聚；（使）逐渐增加；
As with any drug taken in excess, your body can build up a tolerance to it.
和过量服用任何其他药物一样，身体会对它产生耐药性p#ypPvR~SSMrdiU(@3。