Almost every machine with moving parts has wheels，yet no one knows exactly when the first wheel was invented or what it was used for.We do know，however，that they existed over 5,500 years ago in ancient Asia.
The oldest known transport wheel was discovered in 2002 in Slovenia.It is over 5,100 years old.Evidence suggests that wheels for transport didn’t become popular for a while，though.This could be because animals did a perfectly good job of carrying farming tools and humans around.
But it could also be because of a difficult situation.While wheels need to roll on smooth surfaces，roads with smooth surfaces weren’t going to be constructed until there was plenty of demand for them.Eventually，road surfaces did become smoother，but this difficult situation appeared again a few centuries later.There had been no important changes in wheel and vehicle design before the arrival of modern road design.
In the mid1700s，a Frenchman came up with a new design of road—a base layer(层) of large stones covered with a thin layer of smaller stones.A Scotsman improved on this design in the 1820s and a strong，lasting road surface became a reality.At around the same time，metal hubs (the central part of a wheel)came into being，followed by the pneumatic tyre(充气轮胎) in 1846.Alloy wheels were invented in 1967，sixty years after the appearance of tarmacked roads(柏油路)．As wheel design took off，vehicles got faster and faster. (2013·重庆，C)
小题1:What might explain why transport wheels didn’t become popular for some time?
A．Few knew how to use transport wheels.
B．Humans carried farming tools just as well.
C．Animals were a good means of transport.
D．The existence of transport wheels was not known.小题2:What do we know about road design from the passage?
A．It was easier than wheel design.
B．It improved after big changes in vehicle design.
C．It was promoted by fastmoving vehicles.
D．It provided conditions for wheel design to develop.小题3:How is the last paragraph mainly developed?
A．By giving examples.
B．By making comparisons.
C．By following time order.
D．By making classifications.小题4:What is the passage mainly about?
A．The beginning of road design.
B．The development of transport wheels.
C．The history of public transport.
D．The invention of fastmoving vehicles.
小题1:C
小题2:D
小题3:C
小题4:B
小题1: C
解析 细节理解题。从第二段中的“This could be because animals did a perfectly good job of carrying farming tools and humans around.”可知，正确答案为C项。
小题2: D
解析 推理判断题。从第三、四段的描述我们可知，道路的设计为轮子的发展提供了条件。
小题3: C
解析 组织结构题。从最后一段中的In the mid1700s；in the 1820s；At around the same time；in 1967等可看出该段是按时间顺序组织起来的。
小题4: B
解析 主旨大意题。全文主要向我们介绍了车轮的发展历程。