down 与have been down的区别

down 与have been down的区别 have been down 和 have down 区别是? I have been down for two hours.句型转换 I have been down ---- ---- ----. The work （）down by the time you get hereA：will have been down B：is down C：had been downD：would have down 选什么 为什么啊 We should have been so down well的中文翻译是什么 They have been down long as two hours. have been doing,had been doing,will have been down是什么 have been striking down和have been struck down 第一句有语法错误吗?最好有例句 I have been down for two hours.改为同义句I have been down ( )( )（ ）two hours. down down have some down what has been down has been down成分分析 请问i've been down In the picture,all the trees have been cut down.句子中为什么加been I have been asked to have the tree cut down.和I have been asked to cut down the tree.有什么区别么? i think it must have been horrible and damp down there中down there是神马意思? tree after tree went down,cut down by the water,which must have been three metres deepcut down by the water,做什么成分?