Explanation

The fact that the winning pair’s rivals were “in peak physical form” suggests that these rivals had a reasonable expectation of victory; the fact that they “complained about the judging” indicates that they regarded the pair’s victory as not completely deserved. These two considerations suggest that the rivals had a negative reaction to the winning pair’s victory; the only answer choice for Blank (i) that matches this meaning is “irksome,” so it is correct. The second sentence reinforces the implication that the rivals were also strongly deserving of victory, and the word “too” suggests that the performances of the winning pair and of their rivals were comparable in quality. This points to “terrific” as the correct answer choice for
Blank (ii). Thus the correct answer is irksome (Choice B) and terrific (Choice D).
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The phrase "complained in private about judging" indicate rivals are not happy.
In this situation the rivals won't be "unsurprising" or "gratifying"{have pleasure}. They would rather be "irksome" {irritated/annoyed}

The victory of pair will be impressive if, the pair is "terrific"{very great} . But NOT nervous or inconsistent

Hence the answer is Option B,D

The figure-skating pair’s convincing victory last week was particularly (i) _______ to their rivals, who were in peak form and complained privately about the judging. That the pair won when their rivals were (ii) ______ too is also impressive.

The fact that they complained privately about the judging proves that they were not happy and probably very upset with the figure-skating pair's convincing victory. This unhappiness was aggravated by the fact that they were in peak form. The best choice is therefore irksome. We reject unsurprising because the victory was unexpected and surprising since the rivals were in peak form. And the victory was not satisfying for the rivals so we reject gratifying.

The second sentence states why the victory was impressive, a fact already stated. They were in peak form. Therefore we simply need to find a word for "peak" from the choice list for the second blank.

The word is terrific.
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