ever是曾经的意思,一般用在肯定句和
疑问句。
如:(1)I have ever been to America.
(2)Have you ever been to Beijing?
yet可以理解为还、仍然的意思,一般用在否定句与疑问句。
如:(1)I have not finished my homework yet.
(2)Have you prepared for the party yet?
3..just 表 “刚才,方才”,一般用于肯定句中:
如:They've just arrived.他们刚刚到达.
I've just arrived by train,' she said.我刚乘火车到这里,她说道.