重點講解：
1. switch on 打開,開啟(電燈等)；
He didn't bother to switch on the light.
他懶得去開燈XvIlo0^IR^XvE;e。
2. be exposed to 使暴露于；
They were exposed to radioactive fallout during nuclear weapons tests.
在核武器試驗中他們暴露在放射性塵埃之下]nATJe7LM&fhU.。
3. send out 發出(信號、聲音、光、熱等)；
Like bats, they send out sound waves and make sense of their environment from the echoes they receive back.
像蝙蝠一樣，它們發出聲波，然后根據收到的回音來了解周圍的環境yunTSxEh5q-z%]Ni#]。
4. convert into (使)改變；更改；(使)轉變；
The signal will be converted into digital code.
信號會被轉變為數字代碼DA(J2AwhS7gyFLVfk。