1. We learned how to use the right be verbs.

2. We learned how to use the verbs be right.

3. We learned how to use the be verbs right.

4. We learned how to use the verb be right.
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Which ones are correct grammatically?

#1 is good.

#2, 3, & 4 should be, "We learned how to use the be verbs correctly."

In all instances, "correctly" is correct. "right" is colloquial, and often used, but not the best. So #1 could better be, "We learned how to use the correct be verbs."

1. "We learned how to use the right be verbs." - This sentence is grammatically correct. "Be verbs" is a valid term in English grammar, and using "right" to modify it correctly indicates that you learned how to use the correct or appropriate be verbs.

2. "We learned how to use the verbs be right." - This sentence is not grammatically correct. The word order should be "be verbs" instead of "verbs be," and "right" is not correctly positioned to modify "be verbs."

3. "We learned how to use the be verbs right." - This sentence is grammatically correct. "Be verbs" is correctly used, and "right" functions as an adverb modifying "use."

4. "We learned how to use the verb be right." - This sentence is also grammatically correct. Although the singular form "verb" is used instead of "be verbs," it is still acceptable since "be" is a copulative verb. "Right" is positioned correctly as an adverb modifying "use."