cool16 wrote:
Since in this sentence we have shift of tense from present to past , we have to keep verb in second part of comparison (during ellipses ) to convey proper tense of second part , otherwise the second part will confirm the present tense of first part .
Hi
cool16, would just like to add few points to AjiteshArjun's post.
Your observation about the need to
repeat the verb with the correct tense, if the tense is changing, is correct.
However, GMAT shows flexibility in this regard if the implied verb after the comparison indicator is a
simple linking verb (especially
is/was).
This is what's going on here:
....the planet's crust harbors up to three times as much water as (was) previously thought.Since a simple linking verb (
was) is being implied in the second part, it's fine to assume it,
despite the tense change.
There are multiple other examples in
OG:
Industry analysts said that the recent rise in fuel prices may be an early signal that prices of gasoline and heating oil will stay higher than usual through the end of the year.
Again, the actual sentence is:
...prices of gasoline and heating oil will stay higher than (is) usual.... Since a simple linking verb (
is) is being implied in the second part, it's fine to assume it,
despite the tense change.
Another example:
Heating-oil prices are expected to be higher this year than last because refiners are paving about $5 a barrel more for crude oil than they were last year.
Again, the actual sentence is:
Heating-oil prices are expected to be higher this year than (were) last yearSince a simple linking verb (
was) is being implied in the second part, it's fine to assume it,
despite the tense change.
On the other hand, instead of a simple linking verb, if an
action verb is involved
and there is a tense change, then it becomes
mandatory to explicitly mention the verb. So, following would be incorrect:
Peter works harder now than one year back.
Since an action verb (
work) is involved, we need to explicitly mention the verb with the correct tense. So, the correct sentence would be:
Peter works harder now than he did one year back.
This is a great explanation, and the point raised by Cool is valid. However, considering the flexibility GMAT allows one to take, as shown in the examples in
, this is an additional SC rule to remember. Kudos to both, to Cool for raising an important nuance and to EducationAisle for giving good explanation.