[填空题]
The gauge pressure in a /5obpwy)hl:wyy 70 id 3hr g,shelium gwtph1 r/e5f0g2 4fsefas cylinder is initially 28 atm. After many balloons have been blown up, the gauge preth5sf r0f 1 f4wge/2pessure has decreased to 5 atm. What fraction of the original gas remains in the cylinder?