Scientists think the Earth is   21.    . We can see it in the weather.Carbon dioxide, or CO2, is one of the greenhouse gases. People are now makingtoo much CO2. This makes our greenhouse coat   22.   , so our Earth keepsmore and more heat.       Summers are hotter, sea ice is melting. If Earth gets hotter, we are likely tohave more   23.   typhoons, droughts and flooding.What can we do to save our Earth? Take a look at the following things. 1. Use the weather. We can use wind and the sun’s heat to make power. 2. Save the rainforests. Trees take in bad gases like CO2. 3. Replant more trees   24.   we cut them down. 4. Use less plastic bags, plates, and cups. 5. Take public transportation. You can rest or watch people   25.   differentthings. 6.   26.   The more clothes we buy, the more waste we throw away. 

scientist 科學家 greenhouse gas 溫室氣體 melt 融化 drought 乾旱plastic 塑膠 public transportation 大眾運輸

【題組】21.
(A) becomeing the coldest
(B) becoming wonderful
(C) getting better 
(D) getting warmer