Some of the earliest shoes were thought to be foot bags, which were simple pieces of leather that covered the foot. These kept the feet warm and protected them from rocks. Since they were made of light material, it has been difficult for scientists to find proof of this early footwear.
Footwear has come a long way, and now shoes are great at making people run faster, jump higher, and look better. As a matter of fact, some shoes from high fashion designers sell for thousands of US dollars.
◎proof [ pruf ] n.證明；證據（集合名詞，不可數）
◎come a long way 有長足進展
．Television has come a long way over the past 50 years.
◎as a matter of fact 事實上
．Jose thinks his English is good, but as a matter of fact, he speaks very poorly.