It is known that a 32-bit little endian computer system supports 8-bit, 16-bit, and 32-bit data access through byte enable signals. When a program accesses half-word data with an address of 0x1000, which byte enable signals must be effective?已知某32位小字节序计算机支持8b,16b,32b数据访问,当程序访问地址为0x1000的半字数据时,哪几个字节使能信号有效?