2.下列运算中,结果正确的是( )
| A. | 2a+3b=5ab | B. | a2•a3=a6 | C. | (a4)2=a8 | D. | a6÷a3=a2 |
19.如图,其左视图是矩形的几何体是( )
| A. | B. | C. | D. |
18.
如图,直线m∥n,△ABC的顶点B,C分别在直线n,m上,且AC⊥BC,若∠1=40°,则
∠2的度数为( )
0 284142 284150 284156 284160 284166 284168 284172 284178 284180 284186 284192 284196 284198 284202 284208 284210 284216 284220 284222 284226 284228 284232 284234 284236 284237 284238 284240 284241 284242 284244 284246 284250 284252 284256 284258 284262 284268 284270 284276 284280 284282 284286 284292 284298 284300 284306 284310 284312 284318 284322 284328 284336 366461
∠2的度数为( )
| A. | 140° | B. | 130° | C. | 120° | D. | 110° |