15.下列运算正确的是( )
| A. | 2$\sqrt{3}$-$\sqrt{3}$=1 | B. | (-$\sqrt{2}$)2=2 | ||
| C. | $\sqrt{{3}^{2}-{2}^{2}}$=$\sqrt{{3}^{2}}$-$\sqrt{{2}^{2}}$=3-2=1 | D. | $\sqrt{(-11)^{2}}$=±11 |
14.以下四个汽车标志中,是中心对称图形的为( )
0 285956 285964 285970 285974 285980 285982 285986 285992 285994 286000 286006 286010 286012 286016 286022 286024 286030 286034 286036 286040 286042 286046 286048 286050 286051 286052 286054 286055 286056 286058 286060 286064 286066 286070 286072 286076 286082 286084 286090 286094 286096 286100 286106 286112 286114 286120 286124 286126 286132 286136 286142 286150 366461
| A. | B. | C. | D. |