【正确答案】正确答案：In daily conversations people do not usually say things directly but tend to imply them, and according to Grice, they seem to observe willingly or unwillingly certain principle, which is called " Cooperative Principle": " Make your conversational contribution such as is required, at the stage at which it occurs, by the accepted purpose or direction of the talk exchange in which you are engaged". Under this principle, there are four maxims, namely, Quantity, Quality, Relation, and Manner.