Too many present perfect tenses

[kiranck007]

Hi, I find this topic loaded with present perfect tenses, but I don't see any cue on the past event for each of the perfect tense mentioned. Could someone explain, please.

Fusion, the process through which the sun produces heat and light, has been studied by scientists, some of whom have attempted to mimic the process in their laboratories by blasting a container of liquid solvent with strong ultrasonic vibrations.


Fusion, the process through which the sun produces heat and light, has been studied by scientists,
Fusion, the heat and light produced by the sun, has been studied by scientists,
Fusion, the process through which heat and light are produced by the sun, has been studied by scientists,
Scientists have studied fusion, the process the sun uses to produce heat and light,
Scientists have studied fusion, the process the sun uses to produce heat and light, and

[divudu.v]

Is the answer to this Q 'A'?

[kiranck007]

Is the answer to this Q 'A'?

Yes

[jlucero]

Present perfect can stand alone in a sentence to mean something has started in the past and continues through now:

I studied for the GMAT for 3 months (simple past- event is over)
I have studied for the GMAT for 3 months (present perfect- event is still taking place)

[kiranck007]

Present perfect can stand alone in a sentence to mean something has started in the past and continues through now:

I studied for the GMAT for 3 months (simple past- event is over)
I have studied for the GMAT for 3 months (present perfect- event is still taking place)

Hi, Joe. Your examples are ideal. In the sense, they actually reflect the duration. e.g. 3 months. However, in the examples I have provided there is such additional information. Am I supposed to assume in such cases "till now"?

Thanks

[tim]

I'm not sure what the significance of your third sentence is. You start with "however" but go on to confirm a perceived similarity. Your fourth sentence doesn't make sense either. What does it mean to "assume [...] 'till now'"?

[divineacclivity]

Why is 3rd answer choice wrong?

The only difference between A & C is the passive tone ".., the process through which heat & light are produced by the sun, .."
Is the passive tone here absolutely wrong or just less preferred a choice over choice A? Thanks in advance.

A. Fusion, the process through which the sun produces heat and light, has been studied by scientists,

C. Fusion, the process through which heat and light are produced by the sun, has been studied by scientists,

[jlucero]

I very well could be wrong, but I'm not convinced this is from one of our CAT exams. If someone has this question on a Manhattan test that they have taken, let us know which test you found it on (and one of our instructors can take a look at it). If not, let's not discuss issues that don't show up on the real test.

[StaceyKoprince]

Actually, this one came through our filters a couple of weeks ago and we changed answer C (and answer A and B... I changed most of them, actually!). We shouldn't have had a choice that relied solely on passive for elimination - the real test won't do that. Good catch!

Try out the new problem:

Fusion, the process through which heat and light are produced by the sun, has been studied by scientists, some of whom have attempted to mimic the process in their laboratories by blasting a container of liquid solvent with strong ultrasonic vibrations.

A Fusion, the process through which heat and light are produced by the sun, has been studied by scientists,
B Fusion, the process through which the sun produces heat and light, which has been studied by scientists,
C Scientists have studied fusion, the process the sun uses to produce heat and light, and
D Scientists have studied fusion, the process the sun uses to produce heat and light,
E The study of fusion, the process through which the sun produces heat and light, by scientists,

[ElaS308]

Actually, this one came through our filters a couple of weeks ago and we changed answer C (and answer A and B... I changed most of them, actually!). We shouldn't have had a choice that relied solely on passive for elimination - the real test won't do that. Good catch!

Try out the new problem:

Fusion, the process through which heat and light are produced by the sun, has been studied by scientists, some of whom have attempted to mimic the process in their laboratories by blasting a container of liquid solvent with strong ultrasonic vibrations.

A Fusion, the process through which heat and light are produced by the sun, has been studied by scientists,
B Fusion, the process through which the sun produces heat and light, which has been studied by scientists,
C Scientists have studied fusion, the process the sun uses to produce heat and light, and
D Scientists have studied fusion, the process the sun uses to produce heat and light,
E The study of fusion, the process through which the sun produces heat and light, by scientists,

Hi Stacey,

Isn't option A run-on here?
Two complete sentences joined by a comma?
Please clear my misunderstanding?

[RonPurewal]

Isn't option A run-on here?

^^ no.

"some of whom..." is a modifier, just like, "who...".

if that part said "some of THEM...", then that part would become a whole sentence by itself, thus making the entire thing into a run-on. but, that doesn't happen.