Here is the sentence:
On Sunday Michael spent the afternoon waxing
his new car. If he had knew about the two
pop quizzes on Monday, he would have given
his algebra problems and accounting spreadsheets more attention.
The second verb, had knew, is incorrect. As you know, this verb requires the past participle known because of the auxiliary verb had. Know is an irregular verb; the chart below shows its forms.
| Verb | Simple Present | Simple Past | Past Participle |
| know | know(s) | knew | known |
Go to the next sentence, champ!