Time comparison

[FaysalT485]

Hi instructors,

While practicing, i stumbled upon these 2 CORRECT sentences

1) Prices at the producer level are only 1.3 percent higher now than those of a year ago
2) Heating-oil prices are expected to be higher this year than last

The question is:
In the 1st sentence, "those" was required to make it clear that we are comparing the prices of this year with the prices of a year ago. Whereas in the second sentence, nothing of that sort was required after "than", and the rational behind it is that the comparison in the 2nd sentence is between this year and last year rather than being between "heating-oil prices this year" and "heating-oil prices last year". I don't understand when do we restrict the comparison to the year and when do we need to include the subject of comparison in the comparison itself ?

Thanks,

[Sage Pearce-Higgins]

Good find! There appears to be some sort of contradiction between these sentences, and I'd say that it's a bit of a gray area. As you wrote, in the first example 'than those of' is inserted to make sure that we're comparing prices with prices. But the second example is deemed correct even though it seems to compare prices with 'last [year]'.

First of all, I'd note that this issue isn't a critical one in either of those problems. I know the problems well, and in the first there are other ways to eliminate wrong answers. In the second, the other answer choices have much cruder mistakes. When you're studying Sentence Correction, you need to train yourself to look for big issues before dealing with the smaller ones. Bigger comparison issues can be found in problems D83, SC789, and SC792.