We must try our best to stop pollution ______ a low-carbon(低碳)life.

The boy is good at playing _____ guitar and _____ table tennis.

Steven has got the first prize in the math contest. –____ he looks so happy today.

Where may you advise me to start my business? —In my opinion, Yichang is __________one of __________ best places for you.

Grace has ______China for five years. [ ]