I have just arrived by train这里为什么要用现在完成时呢

i have just arrived here 句中arrived 是什么词性 I have just arrived in China为什么要加 have i have just arrived in china为什么加个have have just arrived 和have arrived有什么区别? i have just arrived by train.为什么有have.它起什么作用 I just want to know when you have arrived为什么错了? I have just arrived by train这里为什么要用现在完成时呢 ‘I have just arrived by train,’she said.变成间接引语 --The train has just arrived.--Really?i have waited forone hour. Jimmy writes i have just arrived in London 改为间接引语 i have arrived home 还是i have arrived at home ‘I’ve just arrived by train中的 I have just arrived in Scotland.我就一直没明白到底这个have要怎么用,怎么办? 表状态情绪感觉精神活动的动词,不用现在完成时对吗～I have just arrived by train 这句话对吗 在英语上怎样把直接引语改成间接引语如I have just arrived in Scotland I have just arrived in Scotland. 为什么用in那,in不是在什么的里面的意思吗? Have you been here for a long time?No,I ________here just now.A.have arrived B.arrived in C.arrived 顺便说一下我在学现在完成时 还有理由 为什么啊··· reach,get to的区别?---Have you arrived yet?---Not yet.I have just ____ Beijing.I need another 15 hours.这里应该填什么?