求翻译：本单元谈论的是如何使用过去进行时，这是本单元的重点。本课时是前部分，是一节听说课，初步接触了过去进行时，学好这一部分为后面的学习奠定基础。本课时由When引导的时间状语从句穿插过去进行时的运用，因此要掌握这一用法。是什么意思？

正在翻译，请等待...

This module is talking about how to use the past, this is the focus of the module. This course is the first part, the Section has been heard that lesson, initial contacts on over the past, when studying this part behind for laying the foundations for learning. This lesson from When boot time words p

How this unit discussion is uses when the past carried on, this is this unit key point.This class hour is front the part, is one hears the class, contacted initially when the past carried on, learns this part for the behind study to lay the foundation.This class hour carries on in the past by the Wh

Talking about how to use the past continuous tense in this unit, which is the focus of this module. This class is the front part is a listening lesson, approached the past continuous tense to learn this part lay the Foundation for later learning. This class When the boot time clauses interspersed wi

正在翻译，请等待...