The Third Period—Section B(1a－1e)
Teaching Important Points 【教学重点】
Key words & phrases：
sour，customer
by mistake，in the end
Key sentences：
1.Potato chips were invented by mistake.
2.Potato chips were invented by a cook called George Crum.
Key structure：
S＋was/were＋past participle＋by…
eg：Potato chips were invented by a cook called George Crum.
Teaching Difficult Points 【教学难点】
★Learn more participle verbs to say the passive voice.
Teaching Aids 【教学工具】
