From Manhattan SC online practice questions.

[eybrj2]

Q4. Though viewed from a distance, Saturn's main rings may appear to be smooth and continuous, they are in fact composed of thousands of separate icy ringlets when viewed up close.

a. Though viewed from a distance, Saturn's main rings may appear to be smooth and continuous, they are in fact composed of thousands of separate icy ringlets when viewed up close.

b. Though Saturn's main rings may appear smooth and continuous when viewed from a distance, they are in fact composed of thousands of separate icy ringlets when viewed up close.

c. Saturn's main rings, when viewed from a distance, may appear to be smooth and continuous, though when viewed up close they are in fact composed of thousands of separate icy ringlets.

d. When viewed from a distance, Saturn's main rings may appear smooth and continuous, but closer viewing reveals them to be composed of thousands of separate icy ringlets.

e. Though composed of thousands of separate icy ringlets if viewed up close, the main rings of Saturn may appear smooth and continuous when they are viewed from a distance.

I don't understand the difference between "when viewed up close" and "closer viewing".
To me, both are saying the same thing.

Q5. Though now eaten in large quantities around the world and harmless, the tomato is a member of the generally toxic nightshade family, including belladonna, and was once thought to be poisonous itself as a result.

The explanation for this Q says that "including belladonna" is incorrect left dangling. What does it mean?

Q12. Levels of atmospheric carbon monoxide increased sufficiently during the twentieth century to begin trapping heat radiating from the Earth, causing the average surface temperature to rise.

Is it ok to say that "sufficiently to verb" is the same as "enough to verb"?

Q13. The explanation for Q13 says that ending sentence with such an ~ing verb form is awkward because the reader is left expecting a few more words to complete the thought.

Ex) upon returing (x)
upon his return (o)

Is this rule always correct?

Q17. 17. An economic recession can result from a lowering of employment rates triggered by a drop in investment, which causes people to cut consumer spending and starts a cycle of layoffs leading back to even lower employment rates.

What can be the subject of the verb "starts"?
an economic recession or investment ?

Dose "which" have to be placed before "starts" to be parallel with "causes" ?

[jlucero]

For future reference ask these questions in separate posts to help future students who have similar questions.

#4-

The phrase "when" is they key issue- this denotes that there are only certain times when they are composed of separate icy ringlets.

When viewed up close, they are composed of icy ringlets.

What about when they aren't viewed up close? Do they change form?

When viewed up close, the tv is blurry.

This leaves open the possibility that the tv isn't blurry when I'm not looking up close.

Upon closer viewing, the tv is blurry.

The tv is blurry either way, you just don't notice it unless you look closely.

#5 (I think this should be #7)-

Comma + -ing participles generally modify verbs or full clauses. In this case, "including beladonna" would describe how the subject "the tomato" is a member of the toxic nightshade family. Which is a relative pronoun that must modify the previous word in the sentence "the toxic nightshade family". In general, if you want to modify the previous word in a sentence, use a relative pronoun. If you are modifying a verb or clause that is further away, you will need a comma + -ing participle.

Romans are friends of Greeks, including each other in important discussions (HOW are they friends?).

Romans are friends of Greeks, which includes Country X (Country X is Greek).

#12-

Correct. "Sufficiently to" or "enough to" are both idiomatically fine, but "increase by enough of a percentage" could be reduced down to "increased by enough to", which means we have useless words in a sentence. Or as the GMAT would say- wordy and awkward.

#13-

English grammar seems to always have exceptions! :) So I'm sure you can find exceptions to this. Here's why the sentence "sounds off" though- upon is a preposition and prepositional phrases can only include nouns and modifiers. Returning is a gerund but it's most commonly used as a verb. So it "sounds off" to have a verb in a prepositional phrase. Better to include a modifier for the noun to ensure that the -ing word is functioning as a noun. Or, as the correct answer has, change returning to his return, making it sound more noun-like.

#17-

Again, the word which modifies the word directly in front, so the ending phrase "which causes x and y" both x and y modify the word in front of the which, "investment." The investment causes x and y.

With two things in a list that need to be parallel, you get more leeway in how you can write the sentence. Here's three ways that all work just fine:

The dog caught the ball, which was: (1) red and (2) soggy.
The dog caught the ball, which: (1) was red and (2) was soggy.
The dog caught the ball,: (1) which was red and (2) which was soggy.

It's a lot longer to say the second or third sentence, but all three are parallel because you can take both phrases and attach them after the colon in each sentence.

which: (1) causes people to cut consumer spending and (2) start a cycle of layoffs leading back to even lower employment rates.

Even though you don't need another which here, notice that "causes" and "start" are not parallel.