Cách sử dụng
The expression "top up" means to add more of something, usually to reach a certain level or amount. It can be used in different contexts, such as adding more money to a phone, a transportation card, or a bank account. For example, if your phone credit is low, you can "top up" your phone by buying more credit. If your transportation card is nearly empty, you can "top up" by putting more money on it. In general, "top up" means to add more of something to keep it going or to ensure it has enough to function properly.