What can come after phrase "as well as"?

Question

I am trying to understand the usage of word as. I came across the following sentence.

He is an excellent teacher as well as being a fine musician.

Is it incorrect to write as follows?

1. He is an excellent teacher as well as a fine musician.
2. He is an excellent teacher as well as is a fine musician.

I have a feeling number 1 is correct, but not sure about number 2. I read in Practical English Usage that this is a correct way of writing:

I have to feed the animals as well as look after the children.

In short, can number 2 be used and not be marked grammatically incorrect?

Answer 1

The dictionary explains "as well as":

As well as is a multi-word preposition which means ‘in addition to’:

• She has invited Jill as well as Kate.
• When they go to Austria, they like walking as well as skiing.

It is good to take into account that using "as well as" requires you to pay attention to parallelism. That is why your example:

2. He is an excellent teacher as well as is a fine musician.

is not correct.

It should be either:

He is an excellent teacher as well as a fine musician.

(like your example 1) or:

He is an excellent teacher as well as he is a fine musician.

Answer 2

We see in these examples the following pattern:

[subject] [verb] [argument1] as well as [argument2]

In the example from Practical English Usage, the [verb] is the auxiliary have to. It could have been have to feed, if the part after the as well were a valid argument to feed, but it isn't. So it could have been:

I have to feed the animals as well as the children

In that case, I have to feed would distribute over the animals and the children, meaning:

I have to feed the animals and I have to feed the children.

The PEU example means:

I have to feed the animals and I have to look after the children

Here, the verb have to is distributed over the two arguments, each of which is a verb phrase.

The sentence you are concerned about means:

He is an excellent teacher and he is a fine musician.

Obviously, there is a shared is in this sentence, so we can take that out and distribute it over the two arguments, an excellent teacher and a fine musician:

He is an excellent teacher as well as a fine musician.

The verb appears after as well as in the PEU example because the argument to have to is a verb phrase, while in the teacher example the argument to is is a noun phrase.