Research Writing: That or Which?

Very simple explanation on "that" and "which". But I would say- this one is the best clarification I found on the web so far. I am confident enough now to use either of the two as the papers I review mostly mix up them.

[Originally from Mignon Fogarty]

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Restrictive Clause--That

A restrictive clause is just part of a sentence that you can't get rid of because it specifically restricts some other part of the sentence. Here's an example:

Gems that sparkle often elicit forgiveness.

The words that sparkle restrict the kind of gems you're talking about. Without them, the meaning of the sentence would change. Without them, you'd be saying that all gems elicit forgiveness, not just the gems that sparkle. (And note that you don't need commas around the words that sparkle).

Nonrestrictive Clause--Which

A nonrestrictive clause is something that can be left off without changing the meaning of the sentence. You can think of a nonrestrictive clause as simply additional information. Here's an example:

Diamonds, which are expensive, often elicit forgiveness.

Leaving out the words which are expensive doesn't change the meaning of the sentence. (Also note that the phrase is surrounded by commas. Nonrestrictive clauses are usually surrounded by, or preceded by, commas.
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He as well as Me or He as well as I?

Found a very useful article (don't know the name of the poster in a language forum, but I am acknowledging him/ her with the deepest).

"as well as" functions as a conjunction in #1, not a preposition:

#1. She was into drama and took part in many youth theater productions as well as [took part in] singing in choirs.

"as well as" has two functions:

conjunction: courageous as well as strong.
preposition: The rhetoric, as well as the reasoning, is appreciated.

Notice the commas on each side of the prepositional phrase. They set off or bar the grammar from counting it as part of the subject. That's why the verb is singular "is", and not plural "are". Take the commas away and the prepositional phrase changes identity. It becomes a conjunction + noun phrase that's counted as part of the subject:

conjunction: The rhetoric as well as the reasoning are appreciated.

Below in #2a, there aren't any commas setting off "as well as" from the grammar, so it's counted as part of the subject. "He as well as I" is a compound subject so the verb should be plural "are" (#2b), not singular "is":

#2a. He as well as I is satisfied with the result.
#2b. He as well as I are satisfied with the result.

Subject verb agreement is also a problem for #3a. "He as well as me" is a compound subject; the verb should be plural:

#3a. He as well as me is satisfied with the result.
#3b. He as well as me are satisfied with the result.

Now, add in the commas and "as well as" functions as a preposition,

#2c. He, as well as I, is satisfied with the result.
#3c. He, as well as me, is satisfied with the result.

As a conjunction, "as well as" joins two like forms;i.e., courageous as well as strong; you as well as Sam, but in #3b, below, "as well as" joins two unlike forms, the subject pronoun "He" and the object pronoun "me".

#3b. He as well as me are satisfied with the result.
#3d. He as well as I are satisfied with the result.

Now, "as well as me" is non-standard English, but nevertheless speakers will use "me" as well as "myself" as a way of placing the other person above them. It's a way of humbling oneself.