7．直接写出得数
| $\frac{1}{4}$+$\frac{1}{5}$= | $\frac{5}{51}$×17= | $\frac{1}{4}$×$\frac{2}{3}$×$\frac{4}{5}$= | $\frac{1}{7}$×$\frac{7}{12}$= |
| 24×$\frac{5}{6}$= | 6×$\frac{5}{8}$= | $\frac{1}{3}$+$\frac{5}{6}$+$\frac{2}{3}$= | $\frac{5}{6}$-$\frac{2}{3}$= |
6．下面不可以折成正方体的图形是（ ）
0 157693 157701 157707 157711 157717 157719 157723 157729 157731 157737 157743 157747 157749 157753 157759 157761 157767 157771 157773 157777 157779 157783 157785 157787 157788 157789 157791 157792 157793 157795 157797 157801 157803 157807 157809 157813 157819 157821 157827 157831 157833 157837 157843 157849 157851 157857 157861 157863 157869 157873 157879 157887 199269
| A． |  | B． |  | C． |  | D． |  |