SC's Question number - 803 , 804

803). The period when the great painted caves at Lascaux and Altamira were occupied by Upper Paleolithic people has been established by carbon-14 dating, but what is much more difficult to determine are the reason for their decoration, the use to which primitive people put the caves, and the meaning of the magnificently depicted animals.

(A) has been established by carbon-14 dating, but what is much more difficult to determine are

(B) has been established by carbon-14 dating, but what is much more difficult to determine is

(C) have been established by carbon-14 dating, but what is much more difficult to determine is

(D) have been established by carbon-14 dating, but what is much more difficult to determine are

(E) are established by carbon-14 dating, but that which is much more difficult to determine is


804). The physical structure of the human eye enables it to sense light of wavelengths up to 0.0005 millimeters; infrared radiation, however, is invisible because its wavelength—0.1 millimeters—is too long to be registered by the eye.

(A) infrared radiation, however, is invisible because its wavelength—0.1 millimeters—is too long to be registered by the eye

(B) however, the wavelength of infrared radiation—0.1 millimeters—is too long to be registered by the eye making it invisible

(C) infrared radiation, however, is invisible because its wavelength—0.1 millimeters—is too long for the eye to register it

(D) however, because the wavelength of infrared radiation is 0.1 millimeters, it is too long for the eye to register and thus invisible

(E) however, infrared radiation has a wavelength of 0.1 millimeters that is too long for the eye to register, thus making it invisible

Answers:

803). (OG 10th Ques No - 211) OA - B
OE from OG 10th: Two instances of subject-verb agreement must be observed in this sentence: The period ... has been established and what is much more difficult to determine ... is. Both clauses have singular subjects and must have singular verbs.
A - incorrect - uses the plural form are in the second clause.
C, D - incorrect - use the plural form have in the first clause, and D incorrectly uses are in the second clause as well.
E - incorrect - uses the plural form are in the first clause.
Furthermore, because the date of the period in question was established before the writing of the sentence, the verb of that clause must be in the present perfect form (has been established).

804). (OG 10th Ques no 234) - OA - A
OE from OG 10th - Choice A, the best answer, is clear, idiomatic, and grammatically correct.
B - incorrect - the misplaced participial phrase making it invisible modifies eye rather than wavelength, thus producing a confusing statement that distorts the
meaning.
C, D, E - incorrect - the use of the second it is so imprecise as to be confusing. Furthermore, in D, and thus invisible incorrectly modifies wavelength rather than infrared radiation.
E - incorrect - produces an illogical statement by using a restrictive clause introduced by that where a comma followed by the nonrestrictive "which"
is required: a wavelength of 0.1 millimeters that is too long nonsensically suggests that not all wavelengths of 0.1 millimeters are too long for the eye to register.