Key Words and Useful Phrases Key Words and Useful Phrases Book 7 Unit 4 Book 7 Unit 4learning aims learning aims : : enable the students to master the usage of enable the students to master the usage of the important words and phrases by exercising the important words and phrases by exercising and summarizing and summarizing enable the students to use the newly learnt enable the students to use the newly learnt words and phrases to make up a short passage words and phrases to make up a short pas