He knew he would never forget that day.

Meaning: The boy had information or understanding that he would never lose the memory of that day.

Choice of Words: Knew means to have information or understanding about something. Forget means to lose the memory of something.

Alternative Expressions

He realized he could never erase that day from his memory.

Meaning: This means that he understood that he would never be able to forget what happened that day. It's like saying, He knew that the memories of that day would stay with him forever.

Choice of Words: Realized means to understand or become aware of something. Could is used to talk about ability or possibility. Never means not ever, or at no time. Erase means to remove or delete something. That is used to refer to a specific thing or event. Day means a 24-hour period. Memory refers to the ability to remember things.

That day was etched into his mind, a permanent reminder of what had transpired.

Meaning: This means that the events of that day had left a lasting impression on his mind, and he would never be able to forget them. It's like saying, The memories of that day were so strong that he would never be able to get them out of his head.

Choice of Words: Etched means to carve or engrave something into a surface. Mind refers to the part of a person that thinks and feels. Permanent means lasting forever or for a very long time. Reminder refers to something that helps you remember something else. What is used to refer to a thing or event. Had is used to talk about past events. Transpired means to happen or occur.

Related Expressions