✔ 最佳答案
to-infinitive是絕對可以作為句子既subject,因為不定詞有名詞不定詞,名詞不定詞的功用就如名詞一樣,可以作為主詞,也可以作為受詞。
如:To known oneself is difficult.(了解自己是困難的)
To see you is always a great pleasure(見到你總是快樂)
To err is human, to forgive, divine(犯錯是人之常情,寛恕是超凡的)
To learn a foreign language is no easy task(學習外語是不容易的事)
但此種把to-infinitive置於句首作主詞的用法,如今已極少人用,通常借用it作形式主詞,而將真主詞的不定移到動詞後面,尤其是在口語中最常見到
如:To learn a foreign language is no easy task=It is no easy task to learn a foreign language.
並且因不定詞作主詞時,主詞極易顯得過長,故比較起來,仍然是以,it...to...的用法為佳。
所以你的示句To be a singer is my dream,可寫成It is my dream to be a singer(這句較為普遍)