if you're talking about level huh?, you have to step on the button to drop the box and stop time when it's half way down. then you can hop on it and get to the other side. try it out!
or maybe you're talking about level Gah. you have to press one button right after the other to get two boxes coming down and stop time when the first one is at a height you can hop on. the second one should be higher up at that point and from there you can reach the goal.