英语语法分析

Now, I mentioned this other sentinel value a while back.

现在，我刚才提到了这个标记值。

Some people, such as those on North Sentinel Island in the Andaman Sea, still do.

有些部落，例如居住在安达曼海的北森提奈岛人[1]，现今仍依此为生。

A fireman had placed his back against a tall chimney, and seemed to be acting as sentinel.

一个消防队员靠在高烟囱旁好象在那儿站岗。