---Some English idioms are difficult to understand.---Exactly, _________ you know the meaning of each word.
---Look! The telephone is broken. Someone damaged it ________ purpose. ---That may be right. But perhaps it was broken _________ accident.
Tom kept quiet about the accident ________ lose his job .
He asked me _________ his story .
Father went to his doctor for ________ about his heart trouble .
A good student is good at _______ what the teacher says at once when hearing something important in class .