题目

E-mail, as well as telephones,         an important part in daily communication.    A. is playing      B. have played       C. was playing        D. play 答案：A4．分母是9的最小假分数是$\frac{9}{9}$，最大真分数是$\frac{8}{9}$，最小带分数是1$\frac{1}{9}$．