A website says that "by" in the following sentence is an adverb.

1. The farmer laid by his crops.

But if we analyze, we can see that the word "by" answers the question "what" which makes it a preposition. Also the website says that "crops" directyly receives the action of the farmer and is the direct object of the verb "laid". If it is so then isn't "a small lake" in the following sentence also a direct object of the verb. But here the word "upon" is preposition and "small lake" is its object [indirect object of the verb].

2. We came upon a small lake.

Please clarify this problem.
You can visit the website. http://www.readbygrade3.com/prep.html

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Comments  (Page 2) 
Oh! I wish I had read this before I asked what it meant! Emotion: embarrassed Of course, I wish the poster had not posted the same question twice as well.