They couldn't arrive because they were delayed by?A.heavy traffic B.heavy trafficsC.crowded trafffic.D.crowded traffics.选什么?为什么?根据语法规则是什么?

They couldn't arrive because they were delayed by?A.heavy traffic B.heavy trafficsC.crowded trafffic.D.crowded traffics.选什么?为什么?根据语法规则是什么? They couldn't agree with each other they couldn't have done better是什么意思 They couldn't help ______when they heard the news. 改错They couldn't find such books that they needed. 英语翻译A:Those packages took forever to arrive.B:But they did arrive,didn't they? Mr.Smith's plane___.Let's wait for him here.A.hasn't arrived B.didn't arrive C.doesn't arriveD.couldn't arrive We haven't been told if they ( )on time.If they ( ),I will tell you immediately.A.will arrive,will arrive B.arrive,arriveC.will arrive,arrive D.arrive,will arrive We won't leave until they arrive .这里一定要用arrive为什么? they couldn‘t see anything unusual改成同义句 we couldn't arrive at the station before the train left _______ (没有）the driver's help 翻译:they looked for the treasure for many days,but they still couldn't find any 句型转换:They were so frightened that they couldn't move. They did that because they couldn't understand the nature.这句话哪错了 They couldn't help＿（jump） happy when they heard the news. they were so tired that they couldn't walk any more (同义句转换） They couldn't find the pet.同义句They ____ not ____ ____find the pet. They ----------(look )at the blackboard,but they couldn't ------(see) anything .是不是looked,see?