Veenu21
Hi
GMATNinja,
I have a question regarding the usage of that in this question,
In this sentence:
A South American bird that forages for winged termites and other small insects while swinging upside down from the foliage of tall trees, the graveteiro belongs to the ovenbird family, a group of New World tropical birds that includes more than 230 species and that are represented in virtually every kind of habitat.
a group of New World tropical birds that includes more than 230 species and
is represented in virtually every kind of habitat.
are parallel, so we don't need to repeat "that" after "and'
But, in below question
Researchers have announced that the magnetic fields emitted by one brand of security surveillance system, of which type there are 200,000 worldwide, can interfere with pacemakers
and that this interaction can bring on missed or irregular heartbeats, nausea, breathlessness, dizziness, and even fainting.
Even though both clauses are parallel we are still repeating "that".
Which format is correct?
These are excellent reminders that we can't boil most usage issues down to an ironclad rule. We're talking about two very different sentences here.
Take another look:
Quote:
A South American bird that forages for winged termites and other small insects while swinging upside down from the foliage of tall trees, the graveteiro belongs to the ovenbird family, a group of New World tropical birds
that includes more than 230 species and
that are represented in virtually every kind of habitat.
First, notice that the phrase "that includes" is functioning as a modifier here. Because "includes" must be paired with a singular noun, it seems to be modifying "a group." The parallel construction "that are" must play the same role and therefore modify the same thing as the first element.
But that doesn't work. I can't write "A
group that
includes... and that
are." So this is wrong because it contains a subject/verb disagreement.
The correct answer contains the construction, "
a group of New World tropical birds that
includes more than 230 species and
is..." Notice two things. First, and most importantly, the subject/verb disagreement has been fixed. And second, this option dropped the second "that." There's no rule governing this, but it's a reasonable thing to do here because the parallel verbs are so close together that there's very little risk of confusion for the reader if "that" is removed.
Put another way, it wouldn't have been wrong to write "a group
that includes and
that is," but it isn't necessary.
Contrast the above with the other sentence you mentioned:
Quote:
Researchers have announced
that the magnetic fields emitted by one brand of security surveillance system, of which type there are 200,000 worldwide, can interfere with pacemakers and
that this interaction can bring on missed or irregular heartbeats, nausea, breathlessness, dizziness, and even fainting.
This is a very different beast. "That" in this case isn't modifying a noun. Rather, each "that" is introducing a full clause, giving us
what was announced. So it's playing a different role.
Also, notice how far apart the parallel clauses are. Again, it's not technically wrong to remove the second "that," but if you do, it becomes very very difficult to see what should be parallel to what. So "that" is good here, not because it's required, but because it helps clarify the meaning of a more complicated sentence!
The takeaway: if you're not sure about a "rule," there probably isn't one. Instead, ask yourself which construction is clearer and more logical. No memorization required.

I hope that helps!