I just need some new boxers with a comfortable waistband and a button fly.

我就要买几条大短裤，那种裤腰很舒服的，带扣子的前裆的。

youdao

These and kindred questions need discussion, and need it urgently, in the few years left to us before somebody presses the button and the rockets begin to fly.

这些以及同类的问题需要讨论，而且迫切地需要讨论，就在某个人按下按钮火箭起飞之前给我们留下的这几年里讨论。

youdao

Another way is to have a button that adds new keyword fields on the fly to allow users to add as many keywords as they want.

另一种办法是让按钮随时增加新的关键字，允许用户根据需要添加任意多的关键字。

youdao

Don't fly by your belly button.

FORBES: Magazine Article

This is a walker which has front legs that adjust on the fly with the press of a button, making it possible for a person to use the walker to help get up and down stairs.

FORBES: Innovation For Accessibility

Therefore you're focused on just the most basic movements -- a common one involves jumping in the air, tapping the other button for the downward kick, and then tapping it again to fly backwards.

ENGADGET