why we（主語(yǔ)） cannot do（謂語(yǔ)） that（賓語(yǔ)）.
從句中有主語(yǔ)和賓語(yǔ),那么不缺主語(yǔ)和賓語(yǔ),缺少狀語(yǔ),再加上先行詞是reasons,表原因,所以用why.
where flowers are seen all the year round.
如果是被動(dòng)的不會(huì)劃分,那先還原為主動(dòng)的來(lái)看看.
flowers are seen all the year round.（這里省略了主語(yǔ),原因可查被動(dòng)語(yǔ)態(tài)省略主語(yǔ)的原因）
那么還原成主動(dòng)語(yǔ)態(tài)就是：
We see flowers all the year round.
所以where flowers are seen all the year round 從句里不缺少主語(yǔ)和賓語(yǔ),先行詞是a city,所以要用where .
如果這樣解釋你不能理解,那么你記住從句后如果有主語(yǔ),就是在動(dòng)詞或be動(dòng)詞前面有名詞或代詞,那么從句就不缺少主語(yǔ)和賓語(yǔ),就缺少狀語(yǔ),看看先行詞是什么就可以了.
when he taken away from his mother and sold .
這句你肯定抄錯(cuò)了.從句是被動(dòng)語(yǔ)態(tài).所以應(yīng)該是when he was taken away from his mother and sold .
先行詞是the day ,表示時(shí)間,所以用when,原因同上面的被動(dòng)語(yǔ)態(tài)一樣.