下列一元二次方程中,有两个不相等实数根的方程是( )
A:x2﹣3x+1=0
B:x2+1=0
C:x2﹣2x+1=0
D:x2+2x+3=0
有人问一位当时被称为“纺织大王”的资本家为什么要接受社会主义改造的时候,他说:“是的,我是一个资本家,但是我首先是一个中国人。”“纺织大王”接受的“社会主义改造”是指( )
Thousands of years ago,human(人类)didn’t live in towns.Sometimes they would live in caves(洞穴)or build camps in the forest.Only about thirty people1 in each camp.The men would go hunting while the woman and children2food from trees around the camp.All the food was 3 among people in the group.Every few weeks they moved to another place to find more food.It was a simple life,but people had to be 4 .They had to make everything that they needed,and they had to know a lot about plants and animals.Nowadays most people live in towns and cities,and they work in offices and factories.Life is 5than in the old days.There are fewer 6,but there is less excitement.Some people go7 excitement sailing round the world.climbing mountains,or exploring(探测)caves.Most people look forward to the8,a time when they can enjoy a change from the normal life.For some this means going camping.But camping today is 9 from camping in the past.Gas cookers,ready-made food and air-beds mean people can camp much more10 than they did in the old times.
实验
次数
物重
G/N
物体上升的高度h/cm
测力计的示数F/N
测力计移动的距离s/cm
1
6
3
2.5
9
2
5
17
8
24
如图所示,吊在天花板下面的电灯处于静止状态,如果某一天,吊线突然间断开的同时,所受外力全部消失,则电灯将( )