Even though she never turned back, she knew Tom was behind her. 虽然她没有转身，但却知道汤姆就在她身后。

　　They both turned back to look at the building. 他们同时转身看了看那栋楼。

　　You have a right to turn back if you're scared. 如果你害怕的话，可以回去。

　　A lot of snow is falling. Should we turn back? 正下着鹅毛大雪呢，我们要不要回去？

　　No, let's keep going till we get there.  不，我们得一直走到底。