marcodonzelli
Meteor showers and individual streaks of light that flash across the sky every night are generated when tiny flecks of celestial detritus, often no larger than
grains of sand or of pebbles, burn up speeding through the atmosphere.
(A) grains of sand or of pebbles, burn up speeding
(B) grains of sand or pebbles, burn up while speeding
(C) grains of sand or pebbles, which burn up while speeding
(D) a grain of sand or pebble, which burns up as it speeds
(E) a grain of sand or a pebble, burns up when it speeds
Source :
GMATPREP Default Exam PackThis is what the sentence tells us:
Meteor showers are generated when tiny flecks of detritus burn up while speeding through the atmosphere. These tiny flecks are often no larger than grains of sand or pebbles. The sentence uses ‘or’ to join ‘grains of sand’ and ‘pebbles’ so the two must be parallel.
(A) grains of sand or of pebbles, burn up speeding
Option (A) uses ‘grains of sand or of pebbles.’ What does this mean? It means ‘grains of sand’ or ‘grains of pebbles.’ When we repeat ‘of,’ ‘grains’ is applicable to both sand and pebbles. If we break it into two sentences, we get
often no larger than grains of sand
or
often no larger than grains of pebbles
But ‘grains of pebbles’ makes no sense.
(D) a grain of sand or pebble, which burns up as it speeds
Option (D) uses ‘a grain of sand or pebble’ which is again not correct. We should use ‘a pebble.’ If we split the two parallel parts into two sentences, both should make sense.
… tiny flecks, often no larger than a grain of sand, burn up …
or
… tiny flecks, often no larger than a pebble, burn up …
(without ‘a’ here, the required article would be missing)
(C) grains of sand or pebbles, which burn up while speeding
(D) a grain of sand or pebble, which burns up as it speeds
The use of ‘which’ in options (C) and (D) is incorrect. It makes what follows it a ‘which clause.’ Then we lose the verb of the ‘when’ clause:
when tiny flecks of detritus burn up while speeding through the atmosphere
The subject of the ‘when’ clause is ‘tiny flecks of detritus’ and the verb is ‘burn up.’
When we make it:
when tiny flecks of detritus, … pebbles, which burn up while speeding through the atmosphere
there is no verb for the ‘when’ clause.
Also, ‘which’ seems to refer to ‘pebbles.’ But pebbles are not the ones burning up. The tiny flecks are burning. Hence options (C) and (D) are incorrect.
(E) a grain of sand or a pebble, burns up when it speedsOption (E) uses singular form of verb ‘burns up’ but our subject ‘tiny flecks…’ is plural. Hence option (E) is incorrect.
(A) grains of sand or of pebbles, burn up speeding
(B) grains of sand or pebbles, burn up while speedingAnother issue in option (A) is that 'burn up' is the verb. Here, 'speeding' becomes its object. 'Burn up' what? Speeding. But that makes no sense. We could say 'burn up gases they encounter..' or 'burn up dust particles in the atmosphere' etc. and that would make sense.
Or we could use it without an object so that we know that the 'tiny flecks of celestial detritus' are the ones burning up. This we know is the intended meaning.
Option (B) correctly uses a reduced adverbial clause:
tiny flecks of celestial detritus burn up while speeding through the atmosphere.
Here 'burn up' has no object. The tiny flecks are the ones burning up.
'while speeding through the atmosphere' is a reduced adverbial clause. The actual clause is 'while they are speeding through the atmosphere'. Since the subject is the same (tiny flecks) for both, main and adverbial clauses, we can skip renaming the subject.
'tiny flecks burn up while they are speeding' becomes 'tiny flecks burn up while speeding.'
There are no errors in option (B).
Answer (B)