by the time 到什么時(shí)候?yàn)橹?是一個(gè)完成時(shí)的標(biāo)志用語,后接過去的時(shí)間,主語用過去完成時(shí),后接現(xiàn)在的時(shí)間用現(xiàn)在完成時(shí),后接將來的時(shí)間用將來完成時(shí),本句by the time it ends.接的是句子,英文句子——主將從現(xiàn)原則,即主句和狀語從句都是將來的動(dòng)作,狀語從句一般用一般現(xiàn)在時(shí)表將來,所以雖然是ends,表示的是將來的時(shí)間,故主句用將來完成時(shí),意為：這次會(huì)議到結(jié)束時(shí) 將持續(xù)一整周.介詞by
,by the end of也有類似的用法.例如：We will learned 3000 by the end of next month.
We had learned 3000words by the end of last month.