present at 与 be present at 有什么区别? 怎么用 什么时候不能互换?

present at 与 be present at 有什么区别? 怎么用 什么时候不能互换? attend和be present at有什么区别 at present 与 for the present 区别 in the present和at present有什么区别 at the present time 与 for the present 有什么区别? at the present time与at present 的区别 at present、now、recently有什么区别,at present和recently一样吗? be present at意思 at present怎么读 at present怎么发音? present和at present分别代表什么 用at present造句,