when
英语：unit_6_when_was_it_invented_section_a课件(人教新目标九年级)(2)
ost helpful invention is… A: Why is that? B: Well, it gives/helps people… Who was (telephone) invented by? It was invented by Bell. Henry Ford Edison Bell Ts’ai Lun Wright brothers fisher inventors
when,while和as引导时间状语从句的用法
hile 从句不同的是， as 从句用的一般不用正在进行时，而只是一般过去时。 as 从句一般可以翻 译成“边„„边„„”。 例如： 1. As my mother sang those old songs, tears ran down her cheeks. 当我妈妈唱起那些老歌时，眼泪顺着她的脸颊流了下来。 2. The students took notes as they