And vs Parallelism

As mentioned by the previous posts, you are confusing compound subjects with compound objects. The GMAT will test you on compound subjects, which are plural.

Examples:

Sanjiv, Ravi, and Vinod provide VOIP services. [Compound/plural subject with plural verb]
Sanjiv, with his friends, provides VOIP services. [Singular subject (not plural because 'with his friends' is a modifier) with singular verb]

Regarding your 2nd doubt, 'and' serves as a parallel marker to show when elements of a sentence need to be parallel (or similar). Those elements could be subject nouns (leading to a plural verb), but that is rarely the case. More often the 'and' is creating parallelism between verbs and objects. For example, 'He eats lunch and watches YouTube during his break'. The 'and' creates parallelism between 'eats lunch' and 'watches YouTube'. Those elements are both singular because they refer back to the subject 'he'. The GMAT would test you by altering the structure of those elements: 'He eats lunch and is watching YouTube during his break'. This would not be parallel because the first verb is simple present, 'eats', and the second verb is present progressive, 'is watching'. The tense shift is not parallel.

KW

Thanks You cleared my doubt.

Here is another question

Maria enjoys swimming, hiking , jogging , and bicycling

( Singular Noun : Maria , Singular verb : enjoys )

I enjoy swimming , hiking , jogging , and bicycling

(Singular Pronoun : I, but plural verb : enjoy ) ?
Can you explain this ??

I understand the potential for confusion there. The proper verb form for the first person (singular) subject 'I' is the same as that of plural subjects: I go to the store.... We/They go to the store. While that is confusing, you don't have to worry about it because GMAT does not use 'I' in any of the sentences. In general on the GMAT, you can consider conjugated verbs without an 's' as plural verbs - They walk to school - and verbs with an 's' as singular - He walks to school.

Focus on understanding proper agreement for the 3rd person subjects - He, she, they, etc - and you'll be just fine.

KW

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