a tall round tower standing sentinel over the river镇守在河边的一座高高的圆塔We gave the watchword, and the sentinel let us pass.我们说出口令, 哨兵就把我们放过去了.The lone sentinel walked toward his post.忧愁的哨兵走向岗哨....
Billy leaned forward and brushed a speck of dust off his shoes.比利俯身擦掉了鞋子上的一丝灰尘。I've got a speck of dirt on my shirt.我的衬衫上有一点污垢.Not a speck of cloud is to be seen.看不到一星星云丝....