the quantifier "sound" in "a loud thud" is wrong.

according to the query of Baidu question bank, we know that the quantifiers in "a delicious meal" and "let's go together" are not wrong. The quantifier "sound" in "a loud thud" is wrong, so "mouth" should be used. So the correct sentence should be: "a loud thud."

quantifier, a mathematical and scientific term, is usually used to express the number unit of people, things or actions, and is called quantifier. Such as head, horse, strip, etc.