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Conjunctions - Semantic Categories - Overview

Whereas a typical Master's thesis is approximately one hundred pages long, Ph.D theses is usually over two hundred pages.

Very good!

Incorrect.

This answer choice is grammatically incorrect. The plural subject theses does not agree with the singular verb is.

What helps us identify this question as a Subject Verb Agreement question is the following Stop Sign:

A pseudo-plural singular subject

Thesis is a confusing subject. It ends with -s, which might make us think of it as a plural subject, but it is, in fact, singular. Its plural form is theses.

Incorrect.

While this answer choice corrects the original Subject Verb Agreement mistake by changing the plural subject theses to the singular thesis, it changes the meaning of the original sentence by replacing the opposition word Whereas with the conclusion word so.

Incorrect.

This answer choice repeats the original mistake. The plural subject Ph.D theses does not agree with the singular verb is. This answer choice also changes the correct Master's thesis is to the incorrect Master's theses is.  

What helps us identify this question as a Subject Verb Agreement question is the following Stop Sign:

A pseudo-plural singular subject

Thesis is a confusing subject. It ends with -s, which might make us think of it as a plural subject, but it is, in fact, singular. Its plural form is theses.

Incorrect.

While this answer choice corrects the original Subject Verb Agreement mistake, by changing the plural subject theses to the singular thesis, it changes the meaning of the original sentence by omitting the word usually.

How many times did you spot this Stop Sign in the sentence?

That's probably why you made this mistake.

It is important to memorize Stop Signs as they help us solve questions quickly and efficiently. Once we identify the Stop Sign in a Sentence Correction question, we can search for a relevant mistake in the original sentence or in the answer choices.

This Stop Sign appears twice in this sentence. The second time is Ph.D theses.

Did you miss the second one because you stopped reading after the first Stop Sign?

Remember that a Sentence Correction question may include up to two mistakes. We never stop reading after finding just one mistake since there could be another mistake.

At any rate, we always read the ENTIRE sentence, from beginning to end, both the underlined part and the part which is not underlined.

Since there are up to two mistakes in a Sentence Correction question, we must keep alert for additional Stop Signs even after spotting the first mistake.

Great - you've spotted the Stop Sign which pointed to the original mistakeHowever, you did not spot the Subject Verb Agreement mistake that followed it.

This type of Stop Sign should make us immediately examine the Subject Verb Agreement in the sentence. In this case, the plural subject theses does not agree with the singular verb is.

Also, this Stop Sign appears twice in this sentence. The other time is Master's thesis. Why do you think you missed the first Stop Sign?

It is true that thesis agrees with is. However, the fact the Subject Verb Agreement is correct in the original sentence does not mean other answer choices do not plant mistakes around this Stop Sign.

Keep that in mind when you attempt to answer this question again.

Great - you've spotted both Stop Signs.

However, you did not spot the Subject Verb Agreement mistake that usually follows such Stop Signs. This type of Stop Sign should make us immediately examine the Subject Verb Agreement in the sentence. Though the subject and the verb agree in the first instance of this Stop Sign, it is not the case in the second instance. The plural subject theses does not agree with the singular verb is.

Whereas a typical Master's thesis is approximately one hundred pages long, Ph.D theses is usually
A typical Master's thesis is approximately one hundred pages long, while a Ph.D thesis is generally
A typical Master's thesis is approximately one hundred pages long, so a Ph.D thesis is usually
While typical Master's theses is approximately one hundred pages long, Ph.D theses is generally
Whereas a typical Master's thesis is approximately one hundred pages long, a Ph.D thesis is
Let's look into our working method...
Not even once

Once - Masters Thesis 

Once - Ph.D Theses 

Twice - Master's Thesis and Ph.D Theses 

Yes
No, I read through but I missed it.
I already spotted the second one so I stopped reading
I saw it was grammatically correct so I ignored it