Long, long ago there were only a few thousand people in the world. These people move form place to place over the land, hunting animals for food.
No one knows how or when these people learned about growing food. But when they did, their lives changed. They did not have to look for food any more. They could stay in one place and grow it.
People began to live near one another. And so the first village grew. Many people came to work in the villages. These villages grew very big. When machines appeared(出现), life in the villages changed again. Factories were built. More and more people lived near the factories. The cities grew very big.
Today some people are moving back to small towns. Can you tell why?
小题1:The best title(题目)of the text should be ___.
A．Cities or Villages
B．Back to Towns
C．How Cities Grew
D．People and Animals小题2:The underlined word "they" in the second paragraph refers to(指的是) ___.
A．villages
B．animals
C．cities
D．people小题3:When factories were built, ___.
A．more people live near the factories
B．people began to live in the factories
C．many people began to work in villages
D．many machines appeared in big factories小题4:We can learn from the text that ___.
A．people like to work only in big cities
B．some people don't like to live in big cities
C．there will be no small towns in the future(将来)
D．it is better to live in cities than in villages小题5:In what order did people do the following things?
A. Worked in villages B. Lived near the factories.
C. Learned to grow food. D. Built factories.
E. Began to live near each other.
A. d, b, a, e, c B. e, a, c, d, b
C. c, e, a, d, b D. a. c. d. e. b
______2（填“>”、“=”或“<”）；往该溶液中滴入氯化铵溶液后，
增加，可能的原因是___________________ 
E2Pb(s) +2H+。则脱铅的最合适pH 范围为___（填代号）。