Which of the following statements is not correct with reference to verbs?
1
Primary auxiliary verbs may occur alone as principal verbs in sentences.
2
Auxiliary verbs change according to tense, person, number and gender.
3
If two singular nouns are joined with 'and,' then the verb is plural, except for singular idea expressed through the subject.
4
The function of auxiliary verb is to help the adverbs to express the latter's meaning.