11-23. first.

[X was the first thing that happened.] = Several things happened, but X happened before all the others.

[The woman had her first child two years after she married, and then she had another child three years after that.]

11-24. explain, explains, to explain, explaining, explained.

[X explains something.] = X carefully tells you something you did not know about a thing, or what something means, or what caused something to happen.

[I will show you the parts of this machine and explain what each part does.]

[I can explain what caused these plants to die.]

11-25. by.

[J was caused by K.] = K caused J.

[The food was eaten by the children.]

11-26. lesson, lessons.

[X is a lesson.] = X is something that someone plans and does at a time to help people learn something.

[My school gives me a reading lesson each day.]

[Maybe you can learn to play music, if someone gives you lessons.]

Someone needs to explain what happened here.

Maybe the building __________.

• can explain what happened
• learned a lesson
• was damaged by this round thing