Hello Everyone!
Let's take an in-depth look at this question to determine how to best get to the right answer! First, here's the original question with any major differences between each option highlighted in orange:
The widely accepted big-bang theory holds
that the universe began in an explosive instant 10 to 20 billion years ago and has been expanding ever since.
(A)
that the universe began in an explosive instant 10 to 20 billion years ago and
has been expanding(B)
that the universe had begun in an explosive instant 10 to 20 billion years ago and
had been expanding(C)
that the beginning of the universe was an explosive instant 10 to 20 billion years ago
that has expanded(D)
the beginning of the universe to have been an explosive instant 10 to 20 billion years ago
that is expanding(E)
the universe to have begun in an explosive instant 10 to 20 billion years ago and
has been expandingAfter a quick glance over the options, a couple major differences jump out:
1. How they begin (the universe began / the beginning of the universe was)
2. How they end (has been expanding / had been expanding / has expanded / is expanding)Since verb tenses tend to be easier problems for test takers to spot, let's start with #2 on our list. The writer is trying to convey that the Big Bang started in the past, and the universe started to expand then and is still expanding today.
That means we need to find options that use present perfect progressive tense! Let's see which options best convey this meaning with the correct verbs:
(A) that the universe began in an explosive instant 10 to 20 billion years ago and
has been expanding --> present perfect progressive =
OK(B) that the universe had begun in an explosive instant 10 to 20 billion years ago and
had been expanding --> past perfect progressive =
WRONG (
This suggests that the expansion stopped at some point in the past, which isn't true.)
(C) that the beginning of the universe was an explosive instant 10 to 20 billion years ago that
has expanded --> past perfect =
WRONG (
This suggests the expansion happened before some other past event, which doesn't make sense.)
(D) the beginning of the universe to have been an explosive instant 10 to 20 billion years ago that
is expanding --> present tense =
WRONG (
This doesn't properly show that the expansion started in the past - it just happens in the present, which isn't right.)
(E) the universe to have begun in an explosive instant 10 to 20 billion years ago and
has been expanding --> present perfect progressive =
OKWe can eliminate options B, C, and D because they don't use the correct verb tense to convey the intended meaning clearly.Now that we're left with only options A & E, let's take a closer look to figure out which is the better choice:
(A) that the universe
began in an explosive instant 10 to 20 billion years ago and
has been expandingThis is
CORRECT! It uses the clearest and most accurate verb tenses to convey meaning. It uses past tense to say that the Big Bang "began" in the past, and it "has been expanding" ever since.
(E) the universe
to have begun in an explosive instant 10 to 20 billion years ago and
has been expandingThis option is
INCORRECT because it uses the past perfect "have begun" instead of just using plain past tense to show that the Big Bang happened in the past. There is no other past event in the sentence that happened and ended later, so there's no need for past perfect tense.
There you go - option A was the correct choice all along!Don't study for the GMAT. Train for it.
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