They were randomly divided into four groups and exposed to various noise levels in the background, from total silence to 50 decibels, 70 decibels, and 85 decibels.

他们被随机分为四组，并被置于不同等级的背景噪音环境中，从完全寂静到有50分贝、70分贝和85分贝的噪音。

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The patients were randomly divided into four groups.

患者术后随机分为四组。

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In this test 128 Hailanhe layers aged 190 days were chosen and randomly divided into four groups.

本试验选用190日龄海兰褐蛋鸡(128只)，随机分为四组。

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In a test of creativity, researchers asked 145 students to think of as many unusual uses as possible for such common items as a brick or toothpick, then divided them randomly into four groups.

WSJ: Tactics to Spark Creativity