题目

Let's play basketball ________________ school. A . in B . after C . on 答案：B12．脱式计算$\frac{4}{7}$+$\frac{2}{5}$+$\frac{3}{5}$+$\frac{3}{7}$                    $\frac{5}{9}$×$\frac{3}{10}$+$\frac{5}{7}$÷$\frac{4}{5}$$\frac{1}{5}$÷[（$\frac{2}{3}$+$\frac{1}{5}$）×$\frac{1}{13}$]（$\frac{5}{6}$+$\frac{3}{4}$）×12．