1. He ruminated over the problem.
    他反复思考这个问题。

1. 反刍, 沉思：pillage 掠夺 | ruminate 反刍, 沉思 | rudimentary 根本的, 未发展的

2. 沉思：erudite博学的 | ruminate沉思 | -rumi(入迷)

3. 沈思：ruffle#使皱 | ruminate#沈思 | saddle#使负担

1. 沉思;琢磨;认真考虑
    If you ruminate on something, you think about it very carefully.

    e.g. He ruminated on the terrible wastage that typified American life...
           他认真地考虑了美国生活中典型的严重浪费问题。
    e.g. Obsessional personalities commonly ruminate excessively about death.
           有强迫症的人通常过多地思考死亡的问题。

2. （动物）反刍
    When animals ruminate, they bring food back from their stomach into their mouth and chew it again.

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    e.g. He wanted to have a look at the two oxen, both ruminating without raising their eyes.
           他想看看那两头牛，它们都在反刍，眼睛都不抬一下。

1. reflect deeply on a subject

    e.g. I mulled over the events of the afternoon
           philosophers have speculated on the question of God for thousands of years
           The scientist must stop to observe and start to excogitate

    Synonym: chew overthink overmeditateponderexcogitatecontemplatemusereflectmullmull overspeculate

2. chew the cuds

    e.g. cows ruminate