There must be 3 ml of gasoline left.
Suppose there is an excess of oxygen (the remaining 3 ml of gas is oxygen).
According to the reaction equation, the volume ratio of oxygen and hydrogen in 2 1 ml reaction gas is 1:2.
So 14mL hydrogen and 7mL hydrogen and oxygen reacted.
Then the molecular number ratio in the original mixture is 14:(7+3)=7:5.
On the contrary, the excess hydrogen is (14+3):7= 17:7.