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So it is a comparatively simple step from locating the sea bottom to locating a shoal of fish.

從測定海深到測定魚群，這一進展比較容易。

The degree of secrecy naturally varies considerably.

保密程度自然差別很大。

If it is not a question of resting the body, then perhaps it is the brain that needs resting? This might be a plausible hypothesis were it not for two factors.

如果睡眠的功能不是在于使身體得到休息，那么也許是讓大腦得以休息？若不是下面兩點，這種假使似乎是有道理的。

From the Skeppsbron and surrounding islands the people watched this thing of beauty begin to spread her sails and catch the wind.

人們從斯開波斯布朗和周圍的島嶼前來觀看這艘美麗的戰船揚帆起航，乘風前進。

For our purposes, we are concerned only with one kind of cost----

就我們的目的而言，我們只關心一種費用-

Drinks can be cooled by placing them on ice rather than adding ice to them.

可以把飲料置于冰塊之上來冷卻，而不是把冰塊加進飲料之中。