Cách sử dụng
"Rock solid" is an expression that means something is very strong and sturdy. It can be used to describe a physical object like a building or a bridge that is built to last and won't easily break or fall apart. It can also be used to describe something more abstract, such as a relationship or a promise, that is dependable and reliable. For example, you might say "My friend's support is rock solid" to express that you know you can always count on them.