12.下列运算错误的有( )
①-21+(-21)=0;
②-16+(+4)=-20;
③0+(-13)=-13;
④(+$\frac{5}{6}$)+(-$\frac{1}{6}$)=$\frac{2}{3}$.
①-21+(-21)=0;
②-16+(+4)=-20;
③0+(-13)=-13;
④(+$\frac{5}{6}$)+(-$\frac{1}{6}$)=$\frac{2}{3}$.
| A. | 0个 | B. | 1个 | C. | 2个 | D. | 3个 |
11.下列各数中,与0的和为-$\frac{2}{7}$的是( )
| A. | $\frac{2}{7}$ | B. | -$\frac{2}{7}$ | C. | $\frac{7}{2}$ | D. | -$\frac{7}{2}$ |
10.-10+0的计算结果是( )
| A. | 10 | B. | -10 | C. | 0 | D. | -5 |
9.任何数与零相加,结果( )
0 309812 309820 309826 309830 309836 309838 309842 309848 309850 309856 309862 309866 309868 309872 309878 309880 309886 309890 309892 309896 309898 309902 309904 309906 309907 309908 309910 309911 309912 309914 309916 309920 309922 309926 309928 309932 309938 309940 309946 309950 309952 309956 309962 309968 309970 309976 309980 309982 309988 309992 309998 310006 366461
| A. | 等于这个数的相反数 | B. | 等于零 | ||
| C. | 等于这个数本身 | D. | 为负数 |