research on the forward (backward) principle of twisted car1, research motivationone day, i saw the two-year-old son of the teacher playing a twist-and-twist car. th...

twisted car has always been the first choice for parents to choose car toys for their children. it does not need to charge, fuel, wind, or pedals, and you can drive ...

let me tell you about common sense:one the first thing to learn about figure skating is how to choose a very suitable pair of skates, which is very important.in teac...

how to choose the right skate for you? in response to this problem, gaoxin industry and trade co., ltd. pointed out that before choosing skates, consumers should fir...

before each use of roller skates, all screw caps should be checked carefully, and all loose ones should be tightened one by one.before use, rotate each wheel severa...