中国大学MOOC: Americans apologize if they are late. Some ________ give demerits to students who are late to class.

In thefifth paragraph, the author mainly talks about _________. A: the technical problems of mobile office B: the demerits of working in an office C: the advantages of mobile office D: the distractions in an office

In the jungle, there is usually little time to （） A: recognize where a threat has come from B: compare the benefits of different actions C: weigh merits and demerits of game theory D: escape attacks from powerful predators