eagle eye
(usu sing 通常作单数)
1 very good eyesight 极好的视力.
2 keen watchfulness 敏锐的目光
The teacher's eagle eye was always on us, ie She noticed everything. 教师的锐利目光总是盯著我们(一举一动她都能注意到).
Those planning a trip to remote areas, or intending to live in countries where drinking water is not readily available, should know about the various possible methods for making water safe.