The best time ______ is September and October.
A. to visit Tianjin
B. visited Tianjin
C. to have visited Tianjin
D. to be visited Tianjin
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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
Her job is ______ the garden clean.
A. keep
B. kept
C. keeps
D. keeping
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