Read each pattern and its example, then write your own sentence on the line.
〜ものなら V-potential-dict + ものなら（願望）／V-volitional + ものなら（挑発）
With a potential verb it sets up a wish that is hard to realize: if only I could. With the volitional it becomes a challenge or warning (if you dare). Used in speech and writing.
戻れるものなら、学生時代に戻りたい。 If I could go back, I'd return to my student days.
〜ことだ V-dict / V-nai + ことだ
Gives strong advice about the best way to reach a goal: the thing to do is. Used by a teacher, doctor or senior to someone below them, so avoid it with superiors.
上手になりたければ、毎日練習することだ。 If you want to get good, you should practice every day.
〜ことか どんなに・どれほど・何度 + V / i-adj plain・na-adj な + ことか
An exclamation of strong emotion, usually with どんなに, どれほど or 何度: how very! Slightly literary and emotional; common in speeches and writing.
この日をどんなに待っていたことか。 How long I have waited for this day!
〜ことに V-ta / i-adj い / na-adj な + ことに（感情語のみ）
Puts the speaker's feeling first, before stating the fact: to my surprise, luckily, sadly. Only works with emotion words. Slightly formal, common in written accounts.
驚いたことに、彼は試験に一発で合格した。 To my surprise, he passed the exam on his first try.
〜ことなく V-dict + ことなく
Means without ever doing something, describing how an action was carried out. A stiff written equivalent of 〜ないで; used in reports, news and formal speech.
彼は一度も休むことなく働き続けた。 He kept working without taking a single break.
〜ことから V / i-adj plain + ことから；na-adj な・である + ことから；N である + ことから
Gives the evidence or origin behind a judgment or a name: from the fact that A, B follows. Objective and written; common in news and explanations.
窓が開いていたことから、泥棒が入ったと分かった。 From the fact that the window was open, we knew a burglar had got in.