eye
1.每个人有两个眼睛，但在若干习语里着重在“视”而不着重在眼睛那东西，所以用单数形式。例如：
as far as the eye can reach（在视线以内），have an eye for（有…的鉴别力），have an eye to（照看、觊觎），keep an eye on（注视、留心），with an eye to（着眼于、试图），with a...eye（…地看待），in the eye of（从…的观点看来）
下面各句里也用单数形式：
- There was a happy look in his eye.
- The old man fixed me with his glittering eye.
- She came to the door and her eye peeped in.
2.He was all eyes和He was all eye都作“他很注意地看”解。第一句里的all不可改作both。He stared at us with all his eyes里的all也不可改作both。
