1. [单选题]27． From the passage we know that fresh water doesn't come from________ ．
A. rivers
B. lakes
C. underground
D. the sea
2. [单选题]下列四组物质中，均属于氧化物的是
A. 氧气、氧化钙、四氧化三铁
B. 水、二氧化硫、高锰酸钾
C. C，空气、氧化铜、五氧化二磷
D. 干冰、氧化镁、二氧化锰
3. [单选题]10． Every morning the teacher make students ___________ on the playground．
A. to read
B. reading
C. read
D. reads
