... as if/as though ...
結構︰…as if/as though…現在式/過去式/過去完成式
說明︰此句型意為“彷彿…;好像…一樣”。as if，as though 是<副詞><連接詞>，引導<副詞子句>。<子句>中，可用現在式，以表示事實;也可用過去式或<過去完成式>，分別表示與現在或過去事實相反的<假設語氣>。
He speaks like that as if he doesn’t want to attend the meeting.他那樣說話，似乎不想參加會議。
He walks as if he is drunk. 他走起路來好像他真的醉了。
He felt as if he almost wished to kill them. 他感覺彷彿幾乎要殺掉他們。
The baby opened the book as if he were able to read. 這個嬰兒打開書本彷彿他會念書。
The nurse attends on the patient as if he were her father.
這護士照顧這位病人彷彿在照顧她爸爸似的。
He ran into the room as if he had seen something terrible.
他跑進屋子，彷彿他看到什麼可怕的東西。
She looks as if nothing had happened to her. 她當時看起來好像什麼事都沒發生似的。

It seems/looks as if ...
結構︰It seems/looks as if…
說明︰此句型意為“似乎…”。本句型中的 as if <子句>可用以表示事實，或<假設語氣>。
It looks as if it is going to rain. 好像要下雨了。
It seems as if he knows everything. 他似乎是個萬事通。
It seems as if he knew everything, but in reality, he is as stupid as can be.
他似乎是個萬事通。其實他是再愚蠢不過了。
It looks as if she had just come back from outer space.
她看起來彷彿剛從外太空回來似的。
It seemed as if he had finished the work. 他似乎已經完成了這個工作。
It seemed as if he would never finish the work. 他似乎永遠完成不了這個工作。

If it were not for ...
結構︰if it were not for+名詞/子句，主詞+would/should 等+原形動詞…
說明︰此句型意為“若非(有)…”。此類句構專門用於表示與現在事實相反的<假設語氣>。亦可用“but for+<名詞>”或“without+<名詞>”代替。were 可以提前，省略 if，如例句3。
If it were not for his presence, I would punish you. 要不是他在場，我會處罰你的。
But for your advice, I should have failed. 要不是你的忠告，我會失敗的。
But for music (=Were it not for music), life would be dull. 要不是音樂，人生會很無聊。
If it were not for oxygen and nitrogen in the air, no man could live on the earth.
大氣中如果沒有氧和氮，人就無法生存於地球了。
Without air, all living things would die. 若非空氣，所有的生物都會死亡。
Without newspaper, we would get behind the times. 要不是報紙，我們都趕不上時代了。
I should be lonely, were it not for the birds and the flowers. 我會寂寞，若非有鳥也有花。
Were it not for his help, I could not finish the work.若非有他的幫助，我就不能完成這件工作。
Were it not for science, we could not live a comfortable live.
若非科學，我們無法過著舒適的生活。

If it had not been for ...
結構︰if it had not been for+名詞/子句，主詞+would/should 等+原形動詞…
說明︰此句型意為“若非(有)…”。此類句構專門用於表示與過去事實相反的<假設語氣>。
If it had not been for his help, I should have failed. 如果沒有他的幫忙，我應該已經失敗。
Had it not been for your timely help, our company would have been on the verge of bankruptcy. 若非你及時伸出援助之手，本公司將會瀕臨破產的邊緣。
If it had not been for these experiments, the improvement of the machine would have been impossible. 要不是這些實驗，這部機器也許就不可能改良了。
Had it not been for the kind guide, I might have got lost in the mountains.
要不是這位好心的嚮導，我可能就在山中迷路了。
If it had not been that he was here, I would have punished you.
要不是他在場，我當時就會處罰你。