1+1=?1+2=?1+3=?1+4=?

1/2+1/3+1/4=? 1/2-3/1-4/1= (1-1/2)*(1-1/3)*(1-1/4)*...*(1-1/99)*(1-1/100)= 1+1=?1+2=?1+3=?1+4=? 1+1=?1+2=?1+3=?1+4=? 1/4-1/5=1/18+1/6=1/2-1/8=7/11+5=1/3+1/4=2-1/3= 1+1=?还有1+2+3+4+5=? （1-1/2)+(1/2-1/3)+(1/3-1/4)+.+(1/1999-1/2000)= 1/4*( )=2/3除以( )=7*( )=1 1+1=?1+2=?1+3=? 1+2+3+4= 1+2+3+4= 1+2+3+4=? -4/3×1/2= -1+2-3+4= 1+2+3+4= 1+2+3+4= 巧算：(1+1/2+1/3+1/4+1/5)*(1/2+1/3+1/4+1/5+1/6)-(1+1/2+1/3+1/4+1/5+1/6)*(1/2+1/3+1/4+1/5)(1+1/2+1/3+1/4+1/5)*(1/2+1/3+1/4+1/5+1/6)-(1+1/2+1/3+1/4+1/5+1/6)*(1/2+1/3+1/4+1/5)=====