The wheel is the simplest yet perhaps the most unusual of all inventions, because there are no wheels in nature. No living thing was ever born with wheels.

The prismatic transmission shaft is shown in the figure. Wheels B and D are driving wheels and wheels A, C ,E are driven wheels. If the input powers on driving wheels B and D are equal, the output powers on driven wheels A, C and E are equal too, and if only torsional deformation is considered and bending deformation is not considered, the position of dangerous section is ( ).[img=385x158]1803a368564fb94.png[/img] A: Only in segment AB; B: In segment BC; C: In segment CD; D: In segment AB and segment DE.

When a car turns a corner, the outside wheels must travel((_____))than the inside wheels. A: closer and faster B: farther and faster C: farther and slower D: closer and slower

The plane succeeded in carrying the boy on board with ______ in the air. A: one wheel B: two wheels C: three wheels D: four wheels

The plane succeeded in carrying the boy on board with ______ in the air.A. one wheel C. three wheelsB. two wheels D. four wheels A: two wheels B: four wheels C: three wheels D: The plane succeeded in carrying the boy on board with ______ in the air. E: one wheel

What did “being on wheels” mean in the past?In the past “being on wheels” means _________________.

If only the two of the wheels lose their brakes, the other two wheels will still be able to stop the car．

….,______ up the road with a clumping of boots and a clatter of iron wheels.

The train's wheels are attached to this frame.

ailcar that consists of an uncovered, at bed on wheels