19．Are you ready to take action to protect Planet Earth？You may think it impossible，but you can begin by taking some small，but important，first steps．Many children and their classes in the USA are taking action．
Children Campaign Against Waste
Children are paying attention to the packaging of the things they buy．Packaging includes all the things you throw away when you unwrap（ 打開） anything new．One third of all rubbish is packaging．Mrs Perez's 4th grade class decides to make their school and neighborhood know the waste in packaging．They want people to think before they buy．They also want to let people who make to products know that they want less waste in packaging．So they start a campaign to help people change how they shop．
Children Save Water
Another class decides to help save water．Here's how they got started．
Miguel Salazar lives in Meridien，Texas．Every day he walks home from school and passes Carrollton River．The river is filled with rubbish．But the river was not always this way．Miguel's grandfather remembers flowers and plants grew along it．Many people fished there．So Miguel's class decides to clean up the river．They make a plan．
If one person can make a difference，think how much more can get done if people work together to care for Planet Earth．
49．The children in Mrs．Perez's class start the campaign againstD．
A．water
B．fishing
C．shopping
D．waste
50．Miguel's class project is toC．
A．stop packaging
B．go on a trip
C．clean up Carrollton River
D．talk to families and friends
51．What's the main idea of the passage？A
A．Helping to protect Planet Earth．
B．The problems of pollution in the city．
C．Helping children with their project．
D．How children make their class project．
