4.对于圆的面积公式S=πR2,下列说法中,正确的为( )
0 293794 293802 293808 293812 293818 293820 293824 293830 293832 293838 293844 293848 293850 293854 293860 293862 293868 293872 293874 293878 293880 293884 293886 293888 293889 293890 293892 293893 293894 293896 293898 293902 293904 293908 293910 293914 293920 293922 293928 293932 293934 293938 293944 293950 293952 293958 293962 293964 293970 293974 293980 293988 366461
| A. | π是自变量 | B. | R是常量 | C. | R是自变量 | D. | π和R是都是常量 |