Many useful machines were --1-- by inventors.These machines

Many useful machines were __1__ by inventors.These machines have __2__Many useful machines were __1__ by inventors.These machines have __2__the world a lot.There are many great inventors in the world,and Watt was one of them.Watt was English.When he was a child,he liked to ask questions and he was always __3__hard.One day,he was sitting in the kitchen with his grandmother,he __4__ a kettle(水壶) on the stove(火炉).Soon steam(蒸汽) began to come __5__ the kettle and the lid(盖子) was shaking.Watt asked what was in the kettle.His grandmother said,“Water,my child.”“But I know there’s __6__ in it.It pushes the lid up.” said Watt.His grandmother told him that it was only steam.He asked his grandmother,“__7__ does the steam come up under the lid?”His grandmother said that it came from hot water.Watt said to __8__ ,“The steam will be much strong.It can push things.The steam will be much __9__ if there’s more water.”Later,Watt tried hard and made steam __10__ for people.He invented the first engine.