3.若代数式$\frac{1}{x-1}$在实数范围内有意义,则实数x的取值范围是( )
| A. | x<1 | B. | x>1 | C. | x≠1 | D. | x=1 |
19.南京江北新区包括南京市浦口区、六合区和栖霞区部分街道,规划面积788 000 000平方米.用科学记数法表示788 000 000是( )
| A. | 0.788×108 | B. | 7.88×108 | C. | 7.88×109 | D. | 788×106 |
17.肥皂泡的泡壁厚度大约是0.000 07mm,用科学记数法表示为( )
0 295758 295766 295772 295776 295782 295784 295788 295794 295796 295802 295808 295812 295814 295818 295824 295826 295832 295836 295838 295842 295844 295848 295850 295852 295853 295854 295856 295857 295858 295860 295862 295866 295868 295872 295874 295878 295884 295886 295892 295896 295898 295902 295908 295914 295916 295922 295926 295928 295934 295938 295944 295952 366461
| A. | 7×10-4 | B. | 7×10-5 | C. | 0.7×10-4 | D. | 0.7×10-5 |