19.如果A(1-a,b+1)关于y轴的对称点在第三象限,那么点B(1-a,b)在( )
| A. | 第一象限 | B. | 第二象限 | C. | 第三象限 | D. | 第四象限 |
18.不等式组$\left\{\begin{array}{l}x-3>2\\ x<3\end{array}\right.$的解集是( )
| A. | x<3 | B. | 3<x<5 | C. | x>5 | D. | 无解 |
16.下列标志既是轴对称图形又是中心对称图形的是( )
| A. | B. | C. | D. |
14.方程组$\left\{\begin{array}{l}x-y=3\\ 2x+y=6\end{array}\right.$的解为( )
0 282147 282155 282161 282165 282171 282173 282177 282183 282185 282191 282197 282201 282203 282207 282213 282215 282221 282225 282227 282231 282233 282237 282239 282241 282242 282243 282245 282246 282247 282249 282251 282255 282257 282261 282263 282267 282273 282275 282281 282285 282287 282291 282297 282303 282305 282311 282315 282317 282323 282327 282333 282341 366461
| A. | $\left\{\begin{array}{l}x=3\\ y=4\end{array}\right.$ | B. | $\left\{\begin{array}{l}x=3\\ y=0\end{array}\right.$ | C. | $\left\{\begin{array}{l}x=6\\ y=1\end{array}\right.$ | D. | $\left\{\begin{array}{l}x=6\\ y=-1\end{array}\right.$ |