当你想知道他们是做什么的时候，你会问：
A.What are they doing.
B.What do they do?
C.How do they do?
根据汉语意思选择正确的单词。
环境
A. paper
B. environment
C. litter
根据汉语意思选择正确的单词。
能源
A. fire
B. energy
C. water
April 22nd ____________ World Earth Day.
A. are
B. is
C. was
Everybody should do something ____________ our planet.
A. to save
B. save
C. saving
What ____________ we do to protect our environment?
A. do
B. shouldn't
C. can