VOA慢速英语:Bright Idea: Light Bulbs From Plastic Bottles, Water and Bleach

be used to do被用来做……
例句：Zip codes are used to facilitate mail service. 
邮政编码方便了邮递服务。 

2. First, they filled a two-liter plastic bottle with water and a little bleach.

fill with (使)充〔挤〕满
例句：His eyes filled with tears as he looked lovingly at her.
他深情地望着她, 眼里充满了泪水。

3. Then they used silicone caulk to seal around it to prevent rain from coming in.

prevent from阻止, 防止
例句：His prompt action prevented the fire from spreading.
他的果断行动制止了火势的蔓延。

4. Madina Muhsin, like many of her neighbors, was spending a lot on kerosene to light her home.

spend on把…花在…
例句：He doesn't spend much time on his homework.
他花在作业上的时间不多。

5. If they're given homework, they can finish it on time.

on time按时, 准时
例句：She made a feeble effort to get to school on time.
她努力想按时赶到学校, 但未成功。

6. And they don't have to wait for me to come and light the candle or go outside and do their studies outside so that they can finish their homework.

wait for等待, 等候
例句：He is waiting for something good to turn up.
他正期待着情况好转。

7. It's brighter, and the funny thing is the light bulb actually comes from the place you'd least expect it, which is the trash bin.

come from来自，源出；产自
例句：From this area come most of our best potatoes.
我们最好的马铃薯大部分是这个地区生产的。