15.下列说法中正确的是( )
0 284573 284581 284587 284591 284597 284599 284603 284609 284611 284617 284623 284627 284629 284633 284639 284641 284647 284651 284653 284657 284659 284663 284665 284667 284668 284669 284671 284672 284673 284675 284677 284681 284683 284687 284689 284693 284699 284701 284707 284711 284713 284717 284723 284729 284731 284737 284741 284743 284749 284753 284759 284767 366461
| A. | -a表示负数 | |
| B. | 多项式-3a2b+7a2b2-2ab+1是四次四项式 | |
| C. | 单项式-$\frac{2x{y}^{2}}{9}$的系数为-2 | |
| D. | 若|x|=-x,则x<0 |