Question

my mom laughed at/on the joke

Answer 1

The correct answer will be 'at'.

My mom laughed at the joke.

• The preposition 'at' here is used because it specifies the relationship between the mom and the joke.
• The preposition 'on' is not correct in this case because it is used to specify the position.
• Therefore, the correct preposition in this case will be the use of 'at', because rather than determining the position, the relationship had to be determined.

Answer 2

My mom laughed at the joke.

• To "laugh at" something or someone implies to be entertained by them.
• Although "at" and "on" are both prepositions, "at" is the right option because it can be used with the verb "to laugh" to express the source of amusement.
• One of the most widely used prepositions in English is "at". Several set phrases also employ the preposition "at".
• used to show the situation somebody/something is in, what somebody is doing or what is happening.
• eg:

1. The country is now at war.
2. I felt at a disadvantage

• used with adjectives to show the cause of something.
• eg:

        She was delighted at the result.