I have been sitting 的意思.,时态,相关句子-举例

I have been sitting 的意思.,时态,相关句子-举例 I had been sitting 和 I have been sitting 的区别 have／has been是什么时态?请举例? have been的时态. how long have you been like this?为什么用完成时态?请类似的举例 I have been to shanghai 什么时态 How long have you been doing是什么时态的句子?这个时态怎样构成? I have been successful是什么时态跟I have successed 我想问一下完成时态中 has been ,have heen 和had been 能举例吗, have has been 是什么时态的 关于时态的问题have been I have been sick since yesterday.中have been 是什么是时态为什么要用been.