7.下列各图中,沿着折痕不能折成正方体的是( )
| A. | B. | C. | D. |
6.下面算式( )最适合估计2.875×4.2+7.09的数值.
| A. | 2×4+7 | B. | 2×4+8 | C. | 3×5+8 | D. | 3×4+7 |
5.一个正方形的面积是100平方厘米,把它按1:2的比缩小.缩小后图形的面积是( )平方厘米.
| A. | 50 | B. | 200 | C. | 25 | D. | 20 |
3.用递等式计算,能简算的要简算.
0 136432 136440 136446 136450 136456 136458 136462 136468 136470 136476 136482 136486 136488 136492 136498 136500 136506 136510 136512 136516 136518 136522 136524 136526 136527 136528 136530 136531 136532 136534 136536 136540 136542 136546 136548 136552 136558 136560 136566 136570 136572 136576 136582 136588 136590 136596 136600 136602 136608 136612 136618 136626 199269
| 45×8-120÷15 | $\frac{2}{7}$+$\frac{5}{12}$+$\frac{5}{7}$+$\frac{7}{12}$ | $\frac{11}{17}$÷4+$\frac{1}{4}$×$\frac{6}{17}$ |
| 46.2-15.03-4.97 | [4.5-(0.65×2)]÷0.5 | $\frac{13}{20}$÷[$\frac{1}{2}$×($\frac{3}{4}$+$\frac{6}{5}$)]. |