a). I wish I would have been at the wedding, but I was in India <u>then</u>.
b). Bhutan is one of the least densely populated <u>country</u> in the world
Explanation:
The errors in the above two sentences are the incorrect use of 'then' in the first sentence and the wrong usage of the singular noun 'country' after the phrase 'one of the.' <u>The use of then in the sentence is inappropriate as there is no need to indicate the time as it adds an informal touch to the sentence</u> because <u>it is already understood that the speaker desired to attend the wedding but he couldn't due to being in India</u>. In the second sentence, it is grammatically incorrect to employ a singular noun after the phrase 'one of the' and therefore, it must be 'countries' instead of 'country.'
