Pour 10 liter cup into 3 liters, and then pour 3 liters into 7 liters cup; /kloc-there are 7 liters left in the 0/0 liter cup, then pour in the 3 liter cup, and there are 4 liters left, and pour the 3 liter cup into the 7 liter cup; 10 liter cup pour into 3 liters cup, and the remaining 1 liter cup pour into 7 liters cup, and the 7 liters cup is full.

Precautions:

(1) multiplication principle: if the dependent variable f is in direct proportion to the independent variable X 1, X2, X3...Xn, and each independent variable is qualitatively different, if any independent variable f is missing, it will lose its meaning, then it is multiplication.

(2) addition principle: If the dependent variable F and the independent variable (z 1, z2, z3…,? Zn) is directly proportional to each other, and each independent variable has the same mass. If the dependent variable f still makes sense without any independent variables, it is addition.