Englishfor English speakers
combination
Noun
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A combination is an item or group made of different things or kinds of things.
Any combination of these factors increases the risk dramatically.
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Combination is the process of putting two or more things together.
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math{C}_{n}^{m}/math
drilling
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noun
the act of drilling
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noun
the act of drilling a hole in the earth in the hope of producing petroleum
rig
Noun
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A rig is a machine or piece of equipment that is designed for a specific purpose.
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The rig of a ship is the designs of its sails or masts.