20.已知圆锥的底面半径为3,母线长为8,则圆锥的侧面积为( )
| A. | 48π | B. | 46π | C. | 36π | D. | 24π |
19.下面调查中,适合采用普查的是( )
| A. | 调查全国中学生心理健康现状 | B. | 调查你所在的班级同学的身高情况 | ||
| C. | 调查大东海食品合格情况 | D. | 调查交通法规普及情况 |
16.运用加法的运算律计算(+6$\frac{1}{3}$)+(-18)+(+4$\frac{2}{3}$)+(-6.8)+18+(-3.2)最适当的是( )
0 294117 294125 294131 294135 294141 294143 294147 294153 294155 294161 294167 294171 294173 294177 294183 294185 294191 294195 294197 294201 294203 294207 294209 294211 294212 294213 294215 294216 294217 294219 294221 294225 294227 294231 294233 294237 294243 294245 294251 294255 294257 294261 294267 294273 294275 294281 294285 294287 294293 294297 294303 294311 366461
| A. | [(+6$\frac{1}{3}$)+(+4$\frac{2}{3}$)+18]+[(-18)+(-6.8)+(-3.2)] | B. | [(+6$\frac{1}{3}$)+(-6.8)+(+4$\frac{2}{3}$)]+[(-18)+18+(-3.2)] | ||
| C. | [(+6$\frac{1}{3}$)+(-18)]+[(+4$\frac{2}{3}$)+(-6.8)]+[18+(-3.2)] | D. | [(+6$\frac{1}{3}$)+(+4$\frac{2}{3}$)]+[(-18)+18]+[(-3.2)+(-6.8)] |