Ia 'And' Singular or Plural?

Read the 2 sentences that follow and tell me which one is correct?

1. Mercury, as well as Jupiter, are equidistant from the earth.
   
   
2. Mercury, as well as Jupiter, is equidistant from the earth.
   
   

For all those of you who think the 1st option sounds correct, it's actually the 2nd option that is the correct one.

In case you are wondering why the singular 'is' is correct even though the sentence talks about 2 planets - Mercury and Jupiter - it's because of the use of 'as well as'.

Remember that in the English language, as a rule, only the word 'and' can be used to make compund or plural subjects. Any other word/phrase(called Additives), even if it refers to more than 1 subject, will still be considered a singular subject.

Here are some common additive phrases that do not make compound/plural subjects:

• as well as
• along with
• in addition to
• together with
• accompanied by, etc.
  
  

So,

John, along with his friends, 'is coming for dinner' and not 'are coming for dinner'.

Exception:

When the two parts joined by 'and' are meant to refer to the same person or thing, then go with the singular verb.

Example:

1. Cereal and milk are/is the most common breakfast choice in America.
   
   
2. John's friend and mentor, Jack, is/are coming for tea.
   

In both of the above sentences the correct verb will be the singular 'is' since both 'cereal and milk' and 'friend and mentor' refer to the same thing or person respectively.

To Sum it up:

1. Only the word 'and' can be used to make plural subjects.
   
   
2. All other words/phrases (called additive phrases) will always make singular subjects.
   
   
3. Examples of additive phrases - as well as, along with, in addition to, etc.