_________, I think, and the problems would be settled.
On the long journey, Peter ______a most interesting guide .We all had a wonderful time .
The seller would sell the coat for five dollars, but the customer ______ four dollars.
—I am sorry I didn’t do a good job.—Never mind.________, you have tried your best
Full use should be _______the natural resources to combat the energy crisis.
Our classroom is very clean. Do you know who__cleaned it﹖