twenty trees had been planted by the time we left为什么要用had been planted 这个时态而不是had planted

twenty trees had been planted by the time we left为什么要用had been planted 这个时态而不是had planted 英语翻译Twenty trees wererandomly selected from 30 trees for which the biochemistry of leaves had been previously studied.Three ramets were assigned for the experiment ineach of the ten control trees.In the browsing trees,threeramets were randoml There are twenty more trees to be planted.There are _______ _______ trees to be planted. （ ）Twenty more trees will be planted on the mountain.A.More than twenty B.As many as twentyC.Another twenty D.Twenty different 英语翻译I've bee trying to cheer him up for twenty minutes he won't shop crying There are twenty more trees to be watered.的同义句 There are trees to be watered Twenty. 求大家帮忙翻译一个句子,Twenty trains tried to trek trees. Did you have anyone water the trees?Yes,I had the trees watered. trees bee gees bee是什么意思 'bee''是什么意思? bee是什么意思? bee&honey Bee 是什么意思? THERE WERE TWENTY APPLE TREES ON THE TARM TWENTY APPLE 对划线部分提问i'd like a cd walkman a cd walkman 提问 问道英语对划线部分提问：There are twenty apple trees on the farm.(对划线部分提问,划线部分：twenty速来