What is the future tense of sale?

There is no future tense of sale because the Word sale is a noun. ("I made a sale with the cash register" or "There's a sale on at the store."

You may be trying to ask: what is the future tense of the Word sell, which is a verb. For future tense, you would say "I will sell my car" or "I am going to sell my car." or even "I'm selling my car tomorrow."

So for the future, it is the same Word as in the present tense, but you must add "I will" or "I'm going to" before the Word sell in order to make it future tense.

If you meant to ask about the future tense of the Word sail, as in on a sail boat, you would say "I will go sailing tomorrow" or more commonly "I'm going sailing tomorrow."

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