Question: Sentence 1: He held a large block of the company's stock.
Sentence 2: The pyramids were built with large stone blocks.
Does block mean the same thing in these two sentences?
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Answer: different meanings

Question: Sentence 1: He occupied a post in the treasury.
Sentence 2: Sent via post.
Does post mean the same thing in these two sentences?
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Answer: the same meaning

Question: Sentence 1: Which horse are you backing in this race?
Sentence 2: Back this enterprise.
Does back mean the same thing in these two sentences?
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Answer:
the same meaning