第30次打卡（12月12日）

1）So we've been talking about......press and how we change people's lives.Making  books more accessible to everyone.More books ......more reading.As you know,not every one  has a perfect vision.This increasing literacy in reading......increasing demand for eye glasses.And here something you haven't thought......

2)This increased demand imoact......attitude toward eye glasses.But first, let......and talk about vision correction before the......press.I mean,especially, those few people who were actually  what do people with poor vision do what they do before glass was invented.

3)They have dufferent ways dealing with ......If you think about it, poor vision wasn't the only problem .I mean, thinking about the conditions they lived in. How was it dark?Sometimes ......windows,candles the only source of light.So in some places,like......for example,the wealthy people with poor vision could have someone else to read them.

4)Another solution was something called a reading stone.Around 1000CE Europen month, would take a piece of clear rock and......the top of  reading material.The clear rock magnified the latters,making the ......large. What happens when a drop of water falls on something.Wherever's below the drop of water appears large.The reading stone works in the similar way.

5)But record showed the ......invented in both Europe and China at about the same time.By the way,we call this independent discovery .Independent discovery means when something us invented in different parts the world at the same time.And it is not ......You cal look......textbook to see when things were invented in different cultures at the sames time to see what they talking about.