虛擬語氣5
虛擬語氣用於 名詞性從句 之
表語從句及同位語從句
1) as if /though（似乎，好像，彷彿）引導的表語從句如果表示與現在事實相反，謂語動詞用一般過去時；表示與過去事實相反，謂語動詞用過去完成時；表示與將來事實，謂語用would /might/ could+動詞原形。
It is so cold that it seems as if we were in Siberia. 天真冷好像我們到了西伯利亞似的。
It looks as if it might rain. 看起來好像要下雨。
2) 當表示間接的要求、建議、命令、決定、慾望、勸告、主張等名詞作主語時，其表語從句用虛擬語氣。這類名詞有suggestion, proposal , request, order, advice, idea, demand, recommendation等，其謂語用(should)＋動詞原形。
My suggestion is that we (should) do the experiment again. 我的建議是我們應該再做一次實驗。
My idea is that he (should) do his homework first. 我的想法是他先做作業。
His proposal is that they (should) challenge the other groups to a friendly competition. 他的建議是他們向別的組挑戰進行一場友誼競賽。
上述名詞的同位語從句也用虛擬語氣，其謂語用(should)＋動詞原形。
My suggestion that we (should) do the experiment again is accepted by him. 我提出的我們應該再做一次實驗的建議被他們所接受了。
His proposal that they (should) challenge the other groups to a friendly competition is praised by the teacher. 他提議他們向別的組挑戰，進行一場友誼競賽，受到老師的贊同
Tip: 如果不表示建議、命令、願望等意義時，表語從句及同位語從句中不用虛擬語氣，而用陳述語氣。
