Cách sử dụng
"Double up" means to do something twice or to use something twice as much as usual. For example, if you are cold, you might double up on your socks to keep your feet warmer. Or, if you're late for a meeting, you might double up your pace so that you walk twice as fast as usual. This phrase can be used in a variety of situations and contexts, but it always means doing something twice as much or twice as hard as usual.