肝脏是人体最大的消化腺，分泌的胆汁能够促进下列哪种物质消化（　　）

如图所示，两段等长细线串接着两个质量相等的小球a、b，悬挂于O点．现在两个小球上分别加上水平方向的外力，其中作用在b球上的力大小为F、作用在a球上的力大小为2F，则此装置平衡时的位置可能如下图中的哪幅图（   ）

    A robot is a special kind of machine. It is a machine that can follow instructions( 命令).

    1 it is a machine, it hardly makes mistakes or gets tired. And it 2  complains, unless you tell it to!

    Robots are around us. Some robots are used to 3  things. For example, robots can help make cars. Some robots are used to explore(勘察) dangerous places. Some robots can help clean your house. Some robots can even 4  human languages. They can be used to help answer telephone calls. Some robots look like 5 , but most robots do not. They just look like machines.

    Long ago, people imagined 6 . Over 2,000 years ago, Homer, a famous poet, imagined robots. His robots were made of gold, but they were not 7 . Nobody was able to make a real robot at that time. The  8  real robot was made in 1961. It was called Unimate.

    In the future, we will have even more robots. They will do things that we can't do, or that we don't want to do, or that are too 9 for us. For example, robots will help us fight fires and illnesses and 10 things. They will help make our life better.