Sentence fragment

Question

I have a question about fragment sentences, that is sentences that lack verb or subject. Let's take those two examples from Manhattan sentence correction strategy guide:
 
1. The cat sitting by the stairs watched the mouse. 
2. A new textbook focused on recent advances in artificial intelligence assigned by our instructor.

According to Manhattan's explanation, the first sentence is grammatically correct as it includes a subject (cat) and a verb (watched). On the contrary, the second sentence is fragment because it lacks a main verb. Up to their explanation, for the sentence to be grammatically correct , the sentence should written as "A new textbook ... was assigned" (we should add "was" before the word assigned).

I don't understand what is the difference - in structure - between the two sentences that make's the first sentence right and the second sentence wrong. In other words, why should we add the word "was" to the second question but not to the first sentence?

Thanks in advance!

akshayk · Answer

A new textbook  focused on recent advances in artificial intelligence   assigned by our instructor .

The first highlighted part is a -ed modifier modifying textbook, and the second highlighted part is an -ed modifier modifying intelligence. Hence, this sentence lacks a verb.
Both 'focused' and 'assigned' are NOT verbs here.
We need a form of 'to be' to make them into a verb, and thats why 'was' is used before assigned, making it into a verb.

Correct Sentence - A new textbook focused on recent advances in artificial intelligence  was assigned  by our instructor.
Here 'focused.... intelligence' is describing the new textbook, and this textbook was assigned by the instructor.
=> The textbook was assigned by our instructor. Which Textbook? The one focused on recent advances in artificial intelligence.

For the first sentence, The cat  sitting by the stairs  watched the mouse.
The highlighted part is a  -ing modifier  giving us more information about the Cat.
'Watched' is the main verb of the sentence i.e. the action the cat is performing.
=> The Cat watched the mouse. Which Cat? The one sitting by the stairs.

Does this help?

oryahalom · Answer

akshayk  - thanks for your response! Unfortunately i didn't grasp it :(

Why "assigned by our instructor" modifying intelligence? it seems illogical to me. Why is not the action made in relation to the textbook?

akshayk · Answer

So let’s say the sentence is as follows :

The textbook assigned by our instructor.

The pizza eaten by me.

Are these sentences correct? And if so, what are the verbs?

Sent from my iPhone using GMAT Club Forum

oryahalom · Answer

akshayk  I guess that they are not. It also sound better with "was" before the assigned and eaten, But i want to understand the logic behind it and not rely on my ear. In general "assign" can serve as a verb, So my query boiled down to this issue: in which case that we have a word in the past form, that in general can serves as a verb, it actually plays the role of a verb, and in which it doesn't? In other words - how to identify if the -ed word being used is a Verb or a Modifier?

akshayk · Answer

https://gmatclub.com/forum/ed-forms-ver ... 34691.html This article should help you :) And also re-read the topics on sentence structure, and Subject Verb agreement. Best of Luck mate!

EducationAisle · Answer

Hi  oryahalom , the issue is that for most verbs in English, the  simple past  and  Past participle  are the  same  (such verbs are called  regular  verbs. For example:  assigned  can be used  both  as simple past verb and as Past participle).

This is  not  an issue with  irregular  verbs, for which the simple past and Past participle are  different  (for example:  ate  is simple past while  eaten  is Past participle).

Our book    EducationAisle Sentence Correction Nirvana    discusses a simple framework to distinguish between   simple past verb  and  Past participle   for regular verbs. If someone is interested, PM me your email-id; I can mail the corresponding section.

Suryangshu · Answer

Hi education Aisle please mail that section to me as well. suryangshumukherjee@gmail.com Posted from my mobile device

Alankrita26 · Answer

So in that case is "A new textbook focused on recent advances in artificial intelligence
HAS BEEN assigned by our instructor. " correct ?

EducationAisle · Answer

Yes Alankrita. Good job.

AjiteshArun · Answer

Hi Alankrita26,

If you're asking whether that sentence has a subject and verb combination, then yes, the sentence is correct. The subject is  a new  textbook  focused on recent advances in artificial intelligence , and the verb is  has been assigned .

GmatKnightTutor · Answer

You could break this down to:

A new book has been assigned by John.

Sentence fragment

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