Unit 13 The mystery of the Moonstone

e.g. we were about to start out when it began to rain heavily. 我們正要啟程,就在這時,天下起了大雨。 he had just returned from one business trip when he was asked to make another one. 他剛剛出差回來,這時,又叫他再次出差。 　　4. 表示"每當;每次",相當于every time或whenever。 e.g. she always turns to us for help when she is in trouble.每當她遇到困難,她總是向我們求助。 it is freezing cold here when it snows. 每當這兒下雪,天氣就十分寒冷。 　　5. 表示"當……之后;在……以后",相當于after the time that。 e.g. we went home when the film was over. 電影結束以后,我們回家去了。 　　     when she got home, she started to prepare supper. 她回到家后,開始準備晚飯。 　　二、引導條件狀語從句 　　when引導的條件狀語從句相當于if/ in case引導的條件狀語從句. e.g. when there is no gravity, our feet can no longer stay on the ground. 如果沒有重力,我們的腳就不能夠在地面上站穩。 　　     turn off the switch when anything goes wrong with the machine. 如果機器發生故障,就把電閘關上。 　　三、引導原因狀語從句 　　when引導原因狀語從句時,相當于since/now that引導的原因狀語從句。 　　  e.g. how can they learn anything when they spend all their spare time watching television? 他們把所有的空閑時間都用來看電視了,還能學到什么東西呢? 　　     why do you want a new job when you have got such a good one? 既然你已經有了這么好的一份工作,為什么還要再找新的工作呢? 　　四、引導讓步狀語從句 　　when引導的讓步狀語從句相當于though或although引導的讓步狀語從句。 e.g. he usually walks when he might ride. 雖然有車可乘,但他通常是步行。 　　     the little girl can tell right from wrong when she is only twelve. 這個小女孩雖然只有十二歲,卻能分清是非。 … it was as clear as water…    它（寶石）純凈如水。【點撥】 as clear as water    純凈如水一樣    英語中類似表達有：as blind as a bat(像蝙蝠一樣盲目)               as busy as a bee(像蜜蜂一樣忙碌)
as songful as a bird(像鳥一樣動聽)              as angry as a bull(像公牛一樣憤怒)
as changeful as a chameleon(像變色龍一樣多變)   as bald as an eagle(像鷹一樣禿頂)
as sly as a fox(像狐貍一樣狡猾)                as tall as a giraffe(像長頸鹿一樣高)
as silly as a goose(像鵝一樣愚蠢)               as fast as a hare(像野兔一樣快)