20.下列运算,正确的是( )
①(-5)+(-5)=0;
②(-7)+(+7)=-14;
③0+(-5)=+5;
④(+$\frac{3}{4}$)+(-$\frac{1}{4}$)=$\frac{1}{2}$;
⑤-(-$\frac{5}{8}$)+(-5$\frac{5}{8}$)=-5.
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①(-5)+(-5)=0;
②(-7)+(+7)=-14;
③0+(-5)=+5;
④(+$\frac{3}{4}$)+(-$\frac{1}{4}$)=$\frac{1}{2}$;
⑤-(-$\frac{5}{8}$)+(-5$\frac{5}{8}$)=-5.
| A. | 0个 | B. | 1个 | C. | 2个 | D. | 3个 |