[单项选择]

A wheel is any dish like object that can be used for transportation or in machinery. To be useful, a wheel must revolve (1) an axle, which is normally a shaft attached (2) the wheel’s center.
No one is exactly sure when the wheel was first (3) . But it is thought to have been in use during the early Bronze Age in the Tigris-Euphrates Valley in the Middle East— (4) Iraq is located today. We know that ancient people there used (5) . These and other wheeled vehicles are shown in artwork from the area (6) back to 3500 B.C.
How were such (7) developed The idea began when people placed logs as rollers under a platform. They were used to (8) heavy loads. The center of the logs may have been partly hewn, or carved away, (9) a narrow axle between solid, thick wheels at each end. Some ancient Middle East people even wrapped leather tires around the solid wooden wheels attached to
A. with
B. around
C. by
D. about