Indonesia's Mount Merapi volcano has killed 191 people since it began

Present perfect tense is used if something starts in the past and continuous till the present or its affect is still present in the present. In this sentence the volcano has killed people and the effect is an emergency which is in present. Hence only A and C remains. In C which is used incorrectly. A wins.

Expert, I got this question correct but I have one doubt.

I know that with "Since" we need present perfect tense. Here the clause before "Since" contains present perfect tense whereas clause after since is in simple past tense. Can you please clarify this structure?

Dear RMD007,

I believe that this question slightly confused your basics.

Let's use another example to help you understand the basic concept that's confused you at the moment
1. I moved to Manhattan in 1990 - should be in simple past because that action got over all for once! I moved and then done!
2. I have worked with Google in Manhattan ever since - I still am working with Google from 1990 (perfect way to use present perfect tense)

So how do you put these 2 facts together?

I have worked with Google in Manhattan since I moved to Manhattan in 1990.

Did you see what happened?
Both the present perfect tense and the past tense are in perfect harmony and are describing my situation right now.
I started working with Google in 1990 when i moved to Manhattan and I still am working with Google.

I hope this cleared your confusion.

Awesome explanation, Alok322!

And for any beginners who are reading this (not you, RMD007 -- you already know what's up), you'll want to avoid the common misconception that verb tenses always have to "match" within the same sentence. Verb tenses don't even need to "match" in a parallel structure: if two actions happened at different times, there's no problem using two different verb tenses.

But the GMAT does really, really love to test you on the logic underneath those verb tenses. If the sentence uses more than one verb tense, does the sequence of events logically match those changing verb tenses? Here's a classic pain-in-the-arse: https://gmatclub.com/forum/in-an-effort ... 83910.html

Dear Friends,

Here is a detailed explanation to this question-



Choice A: This answer choice maintains proper tense use and preserves the intended meaning of the sentence. Thus, this answer choice is correct.

Choice B: This answer choice uses the simple past tense verb "killed" to refer to an event taking place in the present. Thus, this answer choice is incorrect.

Choice C: In this answer choice, the modifying phrase "which has lead..." incorrectly modifies the noun "last month". Thus, this answer choice is incorrect.

Choice D: This answer choice uses the past perfect verb "had killed" to refer to an event taking place in the present. Thus, this answer choice is incorrect.

Choice E: This answer choice uses the present perfect continuous tense verb "has been killing", leading to an illogical meaning. The phrase "has been killing 191 people" implies that the volcano has been killing 191 people, gradually. Thus, this answer choice is incorrect.

Hence, A is the best answer choice.

To understand the concept of "Simple Tenses on GMAT", you may want to watch the following video (~1 minute):



To understand the concept of "Past Perfect Tense - Use of Had on GMAT", you may want to watch the following video (~2 minutes):



To understand the concept of "Present Perfect Continuous Tense on GMAT", you may want to watch the following video (~1 minute):



All the best!
Experts' Global Team

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