5.把一条弯曲的公路改成直道,可以缩短路程,用数学知识解释其道理,正确的是( )
| A. | 两点确定一条直线 | B. | 两点之间,线段最短 | ||
| C. | 两点确定一条线段 | D. | 两点之间,直线最短 |
4.单项式-$\frac{2x{y}^{2}}{5}$的系数和次数分别是( )
| A. | $\frac{2}{5}$,3 | B. | -$\frac{2}{5}$,2 | C. | -2,3 | D. | -$\frac{2}{5}$,3 |
3.若a与2互为相反数,则|a+2|等于( )
0 307645 307653 307659 307663 307669 307671 307675 307681 307683 307689 307695 307699 307701 307705 307711 307713 307719 307723 307725 307729 307731 307735 307737 307739 307740 307741 307743 307744 307745 307747 307749 307753 307755 307759 307761 307765 307771 307773 307779 307783 307785 307789 307795 307801 307803 307809 307813 307815 307821 307825 307831 307839 366461
| A. | 2 | B. | -2 | C. | 0 | D. | -1 |