There used to be many green trees in this area in the past .分析一下这个句子结构

there used to be的意思!RT, 请问 There used to be a park. He isn't the man ____he used to be ______ plenty of water in this river.A.There used to being B.there used to beC.There is used to beingD.There was used to be There used to be a clean river.为什么不是There used to have a clean river he used to---（be）a man used to---（tell）lies.分别填什么形式 -------- a small book store in thistown.( they used to be ,it used to have ,there used to be ,there used to have) There used to be.的反义疑问句是怎么样的? there be加used to 的反义疑问句是什么 There used to be some cities wall.的反义疑问句 there used to be an old ciname here,()/()()?反义疑问句 There used to be a lot of pandas,_______ ______? 谁能告诉我 有没有there is used to be there used to be a lot of manatees是什么意思 The old man whose son is in the navy used to be carpenter.请问,used to be carpenter,为什么不是used to be a carpenter. there used to be a reastrant here 与there used to be here a reastrant哪个对 英语there used to be 是过去常有的意思为什么不能用 there are used to be 呢 there used to be a reastaurant here 与there used to be here a reastaurant哪个对