单项选择题A．The man should sit in the back of the classroom.B．The man should go to class.C．The homework was very easy.D．She’s further behind in her work than the man is.

单项选择题A．Many doctors and engineers are sent to the villages to make up for the shortage of experts.B．It is not easy to see the shortage of experts in the villages.C．Expert systems are owned by wealthy farmers and businessmen.D．Expert medical systems are widely used in developing countries.