...同样都有过去的时间状语时,现在完成时的这种用法到底和一般过去时有什么区别呀?例如:重复事件 i have read this book 3 times before 和 i read this book 3 times before.单一事件 i have read this book before 和 i read this book before.
compose和comprise的区别。如题为什么选的是comprise而非compose, The communication relation is defined as the channels through which messages are transmitted by people who ____ a social system.