12.直接写得数.
$\frac{2}{5}$-$\frac{1}{6}$= | $\frac{1}{2}$+$\frac{1}{4}$= | $\frac{5}{6}$-$\frac{1}{2}$= |
$\frac{5}{6}$-$\frac{1}{12}$= | $\frac{3}{17}$+$\frac{2}{51}$= | $\frac{9}{20}$-$\frac{3}{10}$= |
11.小明每天睡眠的时间是8小时,占全天时间的( )
A. | $\frac{3}{4}$ | B. | $\frac{1}{3}$ | C. | $\frac{10}{24}$ |
10.一个棱长是6厘米的正方体,把它锯成3个相等的长方体,表面积增加了( )平方厘米.
A. | 36 | B. | 72 | C. | 144 |
9.小东第一天读了一本书的$\frac{2}{5}$,还剩下这本书的( )没有读.
A. | $\frac{3}{5}$ | B. | $\frac{1}{5}$ | C. | $\frac{2}{3}$ |
8.下面各数中,既是奇数又是合数的是( )
A. | 13 | B. | 25 | C. | 29 |
7.当a等于( )时,17a的积是质数.
0 157815 157823 157829 157833 157839 157841 157845 157851 157853 157859 157865 157869 157871 157875 157881 157883 157889 157893 157895 157899 157901 157905 157907 157909 157910 157911 157913 157914 157915 157917 157919 157923 157925 157929 157931 157935 157941 157943 157949 157953 157955 157959 157965 157971 157973 157979 157983 157985 157991 157995 158001 158009 199269
A. | 1 | B. | 13 | C. | 17 |