Part 1. Definition
In this task, you will be shown a correct English sentence. You need to generate an incorrect form of the input sentence.
Part 2. Example
Students shouldn't work multiple full-time jobs.
Answer: Student's shouldn't work many full-time jobs.
Explanation: The possessive form is not correct in this instance and many should be multiple.
Part 3. Exercise
Otherwise , it will be a problem for us to understand certain things in life . 
Answer:
Otherwise , it will be a problem for us to understand certain thing in life . 