Among the types of word-meaning changes,（）and narrowing are the

Among the types of word-meaning changes,（）and narrowing are the most common by far.
A、degradation
B、transfer
C、elevation
D、extension
【正确答案】：D
【题目解析】：Of these word-meaning changes, extension and narrowing are by far the most common. 在词义变化类型中，词义的扩大和词义的缩小是最为常见的。