In the future，life will be much ____. Maybe there will be vision phones in every ____. People can have a medical examination without a ____ or nurse in the room and do some shopping without ____their homes. And what ____education? There will be ____educational programs on the radio or TV. So many children who live in far-away villages don't need to ____to school every day. They can study at home. Each family has a robot. Robots will ____ people do their housework. Perhaps some people will fly to the ____for a holiday and some people can live under the ____.

下列句子没有语病的一项是（    ）

猜想A：摩擦力的大小与压力的大小有关．

猜想B：摩擦力的大小与接触面的粗糙程度有关．

猜想C：摩擦力的大小与物体运动的速度有关．

为了验证这三个猜想，小华同学设计了如图所示的实验：