求知门径颇多，或阅读或思考或观察或实践。
We gain knowledge by reading, by reflection, by observation or by practice.
求知门径颇多，或阅读，或回忆，或观察，或实践。
We can gain knowledge by reading, by reflection, by observation, or by practice.
求知门径很多，或阅读，或回忆，或观察，或实践。
We can gain knowledge, by reading, by reflection, by observation or by practice.
求知门径很多，或阅读，或回忆，或观察，或实践。
We can gain knowledge, by reading, by reflection, by observation or by practice.
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