household chores

[garib_daas]

E is incorrect because it changes the meaning of the original, suggesting that the figure grew to six hours a week in 1997
rather than by 1997

Ron can you please help illustrate your statement with examples akin to option E for less mortals like us.
the -ING modifier doesn't just suggest that the verb tense is the same; it actually suggests that the action of the modifier occurs in the same timeframe as the stuff that is modified. so, the modifier in (e) illogically suggests that 1981 and 1997 are actually the same timeframe.

Please try to explain in relation to the following example
She slapped Tom, the boy playing the piano.

Ron, Manhantan experts, members, pls, help

I do not understand why E is wrong. In E, the act of doing, here- growing, has tense of the verb of main clause. Specifically,

E means

In 1981 children in the United States spent an average of slightly less than two and a half hours a week doing household chores . That figure GROWED to nearly six hours a week in 1997

So, what is wrong with E.

the -ING modifier doesn't just suggest that the verb tense is the same; it actually suggests that the action of the modifier occurs in the same timeframe as the stuff that is modified. so, the modifier in (e) illogically suggests that 1981 and 1997 are actually the same timeframe.

The difference between B and E is the tense. "had done" is better than "did". Why?, pls, help

the key to the use of the perfect tense here is that we are looking at a completed action, from a standpoint in the past (namely, the standpoint of 1997). for more on that sort of thing, see here:
post58397.html#p58397

[RonPurewal]

She slapped Tom, the boy playing the piano.

--> implies that "playing" is in the timeframe of "slapped". i.e., she slapped him while he was playing.

[vikram4689]

Ron,
I understood the concept how prepositions guide usage of tenses. 2 queries here -
1. Can i say that whenever we use "by" to indicate a time frame e.g. By 1997 (here) ONLY PAST PERFECT will be correct.
In that case a sentence - By 1997 that figure grew to 6hrs/wk - will be INCORRECT ?

2. Earlier i thought that use of Past Perfect in incorrect because 1997 was later event than 1981 but i guess that was a complete ignorance as these 2 events are INDEPENDENT events and the concept that i was trying to apply works only if 2 DEPENDENT events are present in scenario - Just wanted to validate this

[as2764]

also, there's the little matter that memorization is mostly impossible here, anyway; almost every construction that admits the present perfect will also admit the past perfect under different circumstances, and vice versa. for instance, both of the following are legitimate sentences:
for the last five years, i have been nauseated every morning.
for five whole years before i went to see dr. smith, i had been nauseated every morning.
you clearly can't just memorize that "for" goes with xxxxx tense -- but, if you understand the basic pointers above, the use of these tenses should make sense.

wow, those are fine examples you used to explore nuances and intricacies of sentences beginning w/ prepositions. thanks for sharing!

[RonPurewal]

Ron,
I understood the concept how prepositions guide usage of tenses. 2 queries here -
1. Can i say that whenever we use "by" to indicate a time frame e.g. By 1997 (here) ONLY PAST PERFECT will be correct.
In that case a sentence - By 1997 that figure grew to 6hrs/wk - will be INCORRECT ?

no, because "by" can also be used for timeframes that are not in the past.
you must finish the assignment by friday.
i will have graduated by next summer.
etc.

2. Earlier i thought that use of Past Perfect in incorrect because 1997 was later event than 1981 but i guess that was a complete ignorance as these 2 events are INDEPENDENT events and the concept that i was trying to apply works only if 2 DEPENDENT events are present in scenario - Just wanted to validate this

yes

[garib_daas]

Ron, I beg to differ with you.
I think the slapping has already occured (may be a week back), and the modifier the boy playing the piano simply identifies the boy who has been slapped.
Please comment. Your comments are valuable and indispensible for all of us.

She slapped Tom, the boy playing the piano.

--> implies that "playing" is in the timeframe of "slapped". i.e., she slapped him while he was playing.

[garib_daas]

Ron, I am waiting for ur indispensible comments.

Hi Ron,
Can option A be rejected because it contains 2 modifiers of time by 1997 and a week modifying the same verb had spent.
Thereby confusing the meaning.

In 1981 children in the United States spent an average
of slightly less than two and a half hours a week doing
household chores; by 1997 they had spent nearly six
hours a week.
A. chores; by 1997 they had spent nearly six hours
a week
B. chores; by 1997 that figure had grown to nearly
six hours a week
C. chores, whereas nearly six hours a week were
spent in 1997
D. chores, compared with a figure of nearly six hours
a week in 1997
E. chores, that figure growing to nearly six hours a
week in 1997

[RonPurewal]

Ron, I beg to differ with you.
I think the slapping has already occured (may be a week back), and the modifier the boy playing the piano simply identifies the boy who has been slapped.

this could only be true if the sentence were surrounded by context making this meaning absolutely clear -- i.e., context containing an explicit description of a slapping that occurred in the past, as well as an explicit description of piano-playing that is going on right now.
if the sentence stands alone, then the modifier is in the same tense as "slapped".

note that SC sentences always stand alone -- it's sentence correction, after all, not paragraph correction -- so there's no point in considering what you could do to them by adding a bunch of surrounding context.

[RonPurewal]

Can option A be rejected because it contains 2 modifiers of time by 1997 and a week modifying the same verb had spent.
Thereby confusing the meaning.

this notion would eliminate the correct answer as well, so that's trouble.

"a week" can be taken to modify "hours". consider this sentence:
(for) two hours every day, i file tax receipts.
in this sentence, "every day" modifies "two hours", not the following action.