【正文】
t e out. into off down A。t e。如: What happened to you? I happened to see him on my way home.= It happened that I saw him on my way home. doubt 如: He knows the truth without doubt. Step 2 ( B ) child broke his leg _______when he was climbing the mountain. mistake accident chance ( A )2.— What________ to you? — Great changes________there so that I couldn39。t know he did it whether by accident or (2)by accident與 by mistake by mistake I took your umbrella by mistake yesterday. He wrote the word “ fell” by mistake in the Englis