Some past irregular verbs have patterns.
For example, what is the past of bring? What is the pas of think?
What is the past of buy?
What is the past of seek?
What is the past of fight?
Do you notice a pattern?
Brought, thought, bought, sought and fought all end in ‘ought’ (pronounced ‘awt’).
Similarly, the past of catch is ‘caught’ and the past of teach is ‘taught’.
Although written slightly differently, the ‘aught’ ending has the same pronunciation as ‘ought’.
By the way, ‘ought’ can also be written as a separate English word. The word ought indicates duty, for example “he ought to attend English classes” or indicates that something is probable, for example “1 year ought to be enough time to learn English”.
You have now been taught ought!