couldn't 同义句为什么要变过去式用适当的动词和情态动词填空 They couldn't find any secrets.=They ( )not( )to find any secrets.was able问：1.为什么不是were,able2.能否是are ,able？抑或因为could 是can 的过去式

couldn't 同义句为什么要变过去式用适当的动词和情态动词填空 They couldn't find any secrets.=They ( )not( )to find any secrets.was able问：1.为什么不是were,able2.能否是are ,able？抑或因为could 是can 的过去式 We couldn't find them all.变同义句We couldn't find_____of_____. The water was so dirty that we couldn`t drink.变同义句怎么变呀我忘了 It's so big that they couldn't take it with them .这句话的同义句怎么变? It couldn’t be better 为什么用过去式 couldn't是过去式吗 He couldn't answer the question correctly 改为同义句 they couldn‘t see anything unusual改成同义句 The birds couldn't fly in the sky.同义句 He couldn't come back today（改同义句） The birds couldn't fly in the shy.同义句 I couldn't go forward.的同义句是什么,谢谢. He couldn't play anythings 的同义句 He ___play____. The man couldn't believe what said.(同义句)The man couldn't believe what Tom said.(同义句)The man couldn't believe ________ ________. 为什么came要变过去式 为什么这个要变过去式? Because it rained,we couldn't play football的同义句_______ _______the_______,we couldn't play football though he was angry,he couldn't help 改为同义句 ＿＿he was,he couldn't help smiling