solidity-16-ERC721
solidity-15-ERC20
solidity-14-全局变量
solidity-13-可见性
solidity-12-memory-storage
solidity-11-值类型与引用类型
solidity-10-映射-Mapping
solidity-09-结构体
solidity-08-地址-Address
solidity-07-字符串的操作