5．计算各题，写出主要过程．
| $\frac{9}{13}$×$\frac{5}{6}$×$\frac{13}{15}$ | $\frac{11}{24}$÷$\frac{5}{6}$×$\frac{22}{20}$ | $\frac{5}{8}$×$\frac{5}{6}$÷$\frac{25}{36}$ |
| $\frac{11}{7}$÷$\frac{33}{56}$×$\frac{4}{9}$ | $\frac{5}{7}$×$\frac{3}{4}$÷$\frac{15}{28}$ | $\frac{16}{5}$÷$\frac{28}{25}$÷$\frac{3}{42}$ |
4．直接写出得数
| $\frac{11}{15}$×$\frac{25}{44}$= | $\frac{25}{39}$×$\frac{13}{50}$= | $\frac{10}{9}$×6×0= | $\frac{3}{5}$×$\frac{5}{6}$= | $\frac{2}{9}$×$\frac{3}{5}$= |
| 180÷$\frac{9}{10}$= | $\frac{7}{11}$÷14= | 0.8÷$\frac{16}{13}$= | $\frac{1}{5}$×3= | $\frac{2}{5}$×$\frac{5}{8}$= |
18．把下面各组分数通分．
$\frac{3}{4}$和$\frac{2}{5}$； $\frac{5}{6}$和$\frac{7}{8}$； $\frac{4}{9}$和$\frac{5}{12}$．
$\frac{3}{4}$和$\frac{2}{5}$； $\frac{5}{6}$和$\frac{7}{8}$； $\frac{4}{9}$和$\frac{5}{12}$．
16．下列图形不是轴对称图形的是（ ）
0 164590 164598 164604 164608 164614 164616 164620 164626 164628 164634 164640 164644 164646 164650 164656 164658 164664 164668 164670 164674 164676 164680 164682 164684 164685 164686 164688 164689 164690 164692 164694 164698 164700 164704 164706 164710 164716 164718 164724 164728 164730 164734 164740 164746 164748 164754 164758 164760 164766 164770 164776 164784 199269
| A． |  | B． |  | C． |  |