Answer :
Final answer:
A core drill is the best type of drilling machine used for cutting large-diameter holes in concrete floors and walls.
Explanation:
The best type of drilling machine used when large-diameter holes must be cut in concrete floors and walls is a core drill. A core drill is a specialized tool that uses a diamond-tipped drill bit to create clean and precise holes in concrete. It is designed to withstand the tough nature of concrete drilling and can cut through thick layers of concrete with ease.
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