15.在平面直角坐标系中,已知点P的坐标是(-1,-2),则点P关于y轴对称的点的坐标是( )
| A. | (-1,2) | B. | (1,-2) | C. | (1,2) | D. | (2,1) |
12.下列图案中,是轴对称图形的是( )
| A. | B. | C. | D. |
11.下列各组代数式中不是同类项的为( )
0 279351 279359 279365 279369 279375 279377 279381 279387 279389 279395 279401 279405 279407 279411 279417 279419 279425 279429 279431 279435 279437 279441 279443 279445 279446 279447 279449 279450 279451 279453 279455 279459 279461 279465 279467 279471 279477 279479 279485 279489 279491 279495 279501 279507 279509 279515 279519 279521 279527 279531 279537 279545 366461
| A. | $\frac{1}{2}$与2π | B. | -2m2n与2mn2 | C. | 2b2a3与-a3b2 | D. | xy与-yx |