18．学校医务室为预防H7N9禽流感，按药粉和水的比为1：50的标准配制消毒液对全校的各课室进行消毒，现有药粉80克，可以配制出（ ）克消毒液．
| A． | 3920 | B． | 4000 | C． | 4080 |
13．直接写出得数
| 636-198= | 7÷190= | 3.7×0.1%= | 9-0.9= | 0.4×0.2= |
| 72÷0.4= | 305-899= | 7.25+2.75= | 8.1+$\frac{1}{4}$= | 72÷0.4= |
| 24÷$\frac{3}{4}$= | 0.2-$\frac{1}{6}$= | 2÷1%= | $\frac{3}{4}$÷$\frac{1}{2}$= | 1÷$\frac{2}{3}$×$\frac{3}{2}$= |
| 6÷（$\frac{1}{2}$-$\frac{1}{3}$）= | 0.125×8= | 1÷$\frac{2}{3}$= | 2÷1%= | $\frac{1}{2}$÷50%= |
10．小明买了8斤苹果，每斤a元，口袋里还剩b元．小明原有（ ）元．
| A． | 8a+b | B． | 8a-b | C． | b-8a |
9．直接写出得数．
0 156211 156219 156225 156229 156235 156237 156241 156247 156249 156255 156261 156265 156267 156271 156277 156279 156285 156289 156291 156295 156297 156301 156303 156305 156306 156307 156309 156310 156311 156313 156315 156319 156321 156325 156327 156331 156337 156339 156345 156349 156351 156355 156361 156367 156369 156375 156379 156381 156387 156391 156397 156405 199269
| 1×$\frac{11}{12}$= | 2.5×0.4= | $\frac{3}{5}$×$\frac{1}{2}$= | $\frac{1}{3}$×$\frac{1}{4}$= |
| $\frac{1}{4}$-$\frac{1}{5}$= | 9.5+0.5= | $\frac{4}{5}$+$\frac{2}{15}$= | 1-$\frac{1}{4}$-$\frac{1}{2}$= |
| $\frac{3}{2}$×$\frac{2}{5}$= | $\frac{13}{9}×\frac{9}{5}$= | $\frac{5}{6}×12$= | $\frac{5}{9}×4$= |
| $\frac{1}{4}$+$\frac{1}{5}$= | 1+$\frac{1}{2}$= | $\frac{3}{4}×$$\frac{3}{4}$= | 3×$\frac{2}{7}$= |