了如指掌的英文：
[Literal Meaning]
know/as/finger/palm
to know something very well

[解释]
对事物了解得非常清楚，像把东西放在手掌里给人家看一样。

[Explanation]
to know something very well

[例子]
他对这一带的地形了如指掌，所以没有费什么事就找到了泉水。

[Example]
He knew the terrain here very well and found the spring without much trouble.

[英文等价词]
to know something like the palm of one's hand
at one's fingertips

He knew every nook and cranny of the area.
他对这一带的一草一木都了如指掌。

Esau was a farmer and hunter who knew every inch of the country.
伊索是农人，也是猎户，对乡下各地都了如指掌。

The designer is hip to the latest fashion.
设计师对时装的最新款式了如指掌。

No one can be sure about his future.
没有谁能够对未来了如指掌。

Joseph knew the business cold.
约瑟芬对此事了如指掌。

He knew all the surrounding fishing grounds like the palm of his hands.
他对周围的渔场全都了如指掌。

The driver knew the ins and outs of the road.
司机对这条路的一弯一拐，了如指掌。

He' s a taxi Driver, so he knows London like the back of his hand
他是计程车司机,对伦敦市的街道了如指掌

Margaret knew the Franks' report inside out and upside down when she gave her statement on its findings
当玛格丽特就调查结果发表意见时，她已经对弗兰克斯的报告了如指掌。

These pictures are familiar to all who take an interest in such things.
所有热衷此道的人对这些画已了如指掌了。