—Why do you look so puzzled?—Oh，I ________ over a most difficult maths problem.

He will come to call on you the moment he ______his painting.

The version _______ to be closest to the author’s original now belongs to a national museum in Paris.

Profits in his company went up by 25% last year,and _____ so far this year though the  financial situation is bad.

Jiangsu Province ____ a series of activities to protect water resources over the past few months. Early this year, several cities ___ citizens to use new types of toilet equipment.