1 . It wasn’t long before we were surrounded by enormous sand dunes ________(tower) above us on all sides. （所给词的适当形式填空）

2 . It wasn’t long before we were surrounded by enormous sand dunes t________ above us on all sides. (根据首字母单词拼写)

3 . Three mountains, Meili, Baimang and Haba, t________ over the land, are covered with snow.