since 和 when在现在完成时中的区别比如 I have been skating since I was7 years o_英语解答

since 和 when在现在完成时中的区别
比如 I have been skating since I was7 years old 为何不能用when 什么时候用when
多举几个例句然后分别说明主句从句接什么时态
别复制长帖子 3Q

人气：351 ℃　时间：2020-02-27 03:06:50

解答

since指从过去一时刻到现在：I have been skating since I was7 years old .
when强调时间点：I had finshed my homework when he go home.