One of the ways ______ the amount of greenhouse gases that we put into the air is to buy products that don't use as much energy.
A. reducing
B. to be reduced
C. reduced
D. to reduce
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The best time ______ is September and October.
A. to visit Tianjin
B. visited Tianjin
C. to have visited Tianjin
D. to be visited Tianjin
Some people use less energy by ______.
A. carpool
B. to carpool
C. carpooling
D. being carpooled
______ is fun and a great way ______ greenhouse gases.
A. Plant trees, reduce
B. Planting trees, to reduce
C. To plant trees, reduce
D. Planting trees, to reducing
______ on Mount Panshan in Jixian County is a good choice in this season.
A. Take a hike
B. Taken a hike
C. Taking a hike
D. Having taken a hike
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