he will have been playing on the piano by that time 为什么要用on the?去掉会怎么样呢?意思是他将一直弹钢琴到那个时候。

he-----blind not to see that car cominga can hve been b will have been c may have been d must have been By next year,he ( ) twenty years old.A will beB will have been 为什么B不行 who will have been to 求助壹道英语题、、、谁能帮帮莪?How long ________ teaching?Forty years.A.will he have been B.he will have been C.will have he been D.will have been he先O(∩_∩)O谢谢大家囖~~~~~~~~THANK YOU~~~~~~~~~~~~ By the end of this month he will have been training horses／climbing mount by the time he arrives in beijing ,we ___here for two daysA will have stayed B have been staying By the time he arrives in Beijing, we ________ here for two days.A. will be arriving B. have been stayingC. have stayed D. will have stayed By the time he arrives,all the work __,with __our teacher will be content.A.will have been accomplished;whichB.will be accomplished;thatC.will have accomplished;itD.had been accomplished;him He should have been at boarding school should have been He had been a doctor for five years by the time he ____from the medical schoolA:will graduate B:will have graduated C:graduates D:graduated will have been sold out 是什么语法 I have been around will accompany you will have been done怎么用 28.--- Is Tom still smoking?　　--- No.By next Saturday he ______ for a whole month without smokiA.will be B.will have gone C.will have been D.has been going Either he or his parents _____going to Japan tomorrow morning.A is B are C will be D have been 1.The work____ by next weekA.will have been finished B.will have finishedC.has been finished D.would have finished2.Bill___a job in a factory,but he refused to take itA.was offering B.offeredCwas offered D.had offered He is said to have been there have been doing,had been doing,will have been down是什么