At the end of one month, the boys looked forward to their mother’s return most earnestly, as they were really tired with their father’s boiled eggs.()

A. There are many kinds of amusements you can enjoy without spending much money.
B. Local colleges often hold meetings to debate the issues people are interested in.
C. The film shown at the local public library is often free of charge.
D. You should be a tourist if you want to know more about the city you live in.

A. working efficiency that leads to the highest output
B. the working skills and the working environment
C. the techniques leading to the highest productivity
D. the use of workers to get the greatest profit