介绍:
Four minutes is all it takes for the sand inside an egg-timer to run from the top to the bottom. And that just the right time to boil an egg. Sandglasses are simple and accurate, and have been used for hundreds of years. Once the timer has finished, you just turn it upside down to start again!
1.egg-timer：煮蛋计时器
2.upside：上面
关注微信公众号ettalk365,获取更多学习内容。
sophia微信：sophia_ettalk
微博：Sophia的英语学堂
