Question

64 in looking directly at a flower the image is not produced, but it appears immediately as the direction of the eye is altered. again, by looking sideways on the object, a double image is seen for a moment, for the spectrum then appears near and on the real object.
the twilight accounts for the eye being in a perfect state of repose, and thus very susceptible, and the color of the poppy is sufficiently powerful in the summer twilight of the longest days to act with full effect and 65 producing a compensatory image. i have no doubt these appearances might be reduced to experiment, and the same effect produced by pieces of colored paper. those who wish to take the most effective means for observing the 66 appearance in nature—suppose in a garden, should fix their eyes on the bright flowers selected for the purpose, and, immediately after, look on the gravel path. this will be seen studded with spots of the opposite color. the experiment is practicable on a cloudy day, and even in the brightest sunshine, for the sunlight, by enhancing the brilliancy of the flower, renders it fit to produce the compensatory color sufficiently distinct to be perceptible even in a bright light. thus, peonies produce beautiful green, 67 marigolds vivid blue spectra.
as the opposite color is produced by a constant law in experiments with colored objects on portions of the retina, so the same effect takes place when the whole retina is impressed

1. could perceive

a) no change
b) could have perceived
c) were perceiving
d) would have perceived

1. in

a) no change
b) therefore
c) and
d) whereas

1. producing

a) no change
b) produced
c) produce
d) produces

1. appearance in nature—suppose in a garden, should

a) no change
b) appearance—in nature (suppose in a garden) should
c) appearance in nature—suppose in a garden—should
d) appearance in nature, suppose in a garden—should

1. marigolds

Explanation:

• 64: "In" is incorrect here. The context requires a word to show a result - "Therefore" is appropriate as it indicates a consequence.
• 65: The verb form should be parallel to "act". "Produce" should be used to match the base - form of the verb in the earlier part of the sentence "to act with full effect".
• 66: The dash usage in the original is incorrect. Parentheses should be used to set off the non - essential "suppose in a garden" as it is an aside within the main clause.
• 67: No error. The sentence is grammatically and semantically correct as written.

Answer:

1. B. Therefore
2. C. produce
3. B. appearance—in nature (suppose in a garden) should
4. A. NO CHANGE