1．The Roman Empire existed(存在) for several centuries.
2．The enemy attacked(进攻) on the left flank(左翼)．
3．He was frightened(胆战心惊) at the thought of his huge debts.
4．When he moved to Canada, the children adapted(适应) to the change very well.
5．Fishermen and sailors sometimes claim(声称) to have seen monsters in the sea.
6．He was calm(平静的) when I told him the bad news.
7．He is unlikely(不可能的) to come because he is very busy.
8．A mysterious(神秘的) illness is affecting all the animals.
9．I was unaware of his existence(存在) until today.
