Sound samples and guide 语音样本及练习说明

Sound samples 语音样本: 

Exercises 3 & 4 mentioned in the PDF file will be given as Exercises 1 & 2 in the next Unit. At the same time, Exercises 3, 4 & 5 are not mentioned in the PDF file.

以下PDF文件中提到的练习3、练习4将作为下一讲的练习1、练习2给出。同时,本讲中的练习3、练习4、练习5在以下PDF文件中没有提及。