" Nobody knows who invented the wheel." I know "the wheel" is a generic use, which means a type of objects.<br/><br/>Are the following sentences correct? <br/><br/>A wheel / The wheel is used for making transportation fast and smooth. 1<br/><br/>Wheels are used for making transportation fast and smooth. 2<br/><br/>a wheel, the wheel, wheels , are all these in generic use? Thanks.