3/ ERC-20 functions:
ERC-20 contains functions like totalSupply, balanceOf, transfer, transferFrom, approve and allowance to facilitate trading and transfers and their interaction with smart contracts.
3/ERC-20功能：
ERC-20包含totalSupply、balanceOf、transfer、transferFrom、approve和Association等功能，以促进交易和转让及其与智能合同的交互。