阅读下面短文，从短文后各题所给四个选项（A、B、C和D）中，选出可以填入空白处的最佳选项。
Robots seem very new to most people. But they have a 1 history. A Greek scientist made the first robot. You may 2 robots in some movies. The robots in the movies are usually stronger, faster and 3 than people. In real life, most robots are used in factories. They can do lots of dangerous, difficult or4 jobs. Some people can't look 5 themselves and robots can help them. For example, some people can't see, and they use a guide dog to help themselves move. But now scientists are making a 6 to help them.
Robots are also used in American hospitals. At one hospital, a robot 7 meals from the kitchen to the sick people's rooms. It never loses its 8 because it has a map of the hospital in its computer system(系统). 9 the future, robots will even work in space. But robots will 10 take the place of(代替)people but only work for people. They can, however, help us in a lot of different ways.
物组织中提取DNA进行分析，其四种碱基数的比例是鸟嘌呤与胞嘧
啶之和占全部碱基数的46%，又知该DNA的一条链(H链)所含的碱基中28%是腺嘌呤，则与H链相对应的另一条链中腺嘌呤占该链全部碱基数的
