Just wondering, can the second form be used in sarcasm? For example: "誰もいないね。このケーキを食べるしかないね。"
Also, I noticed some of the sentences end in しかないだ while others just end in the しかない. That confuses me a little...
Yes, you can use しかない as per your example sentence.
As for the だ: ない here is just ありません or the negative form of the verb you're using so the same rules apply as when you're using the negative form in other sentence constructs.
Did that answer your question? :o
Hmmm, I don't quite get it. The explanation says one needs to use a verb in nai-form, but then there is an example like 作ぶんを一まいしか書きませんでした。 Is this 書きませんでした also a nai-form of a verb? Sorry, if that's a silly question, I just got a bit confused.
it is the polite form of the negative. For 書く, you've got
書かない (short negative)
書きません (polite negative)
The でした is the past tense.
Teeeeechincally, only the first is the 'ない' form, but it would take up too much space to add every negative form. Maybe ..use 'Negative form' in the box in the future.
I got tripped up on a grammar question relating to this - I commented in the quiz but it seems worth mentioning here too. Of the given options, 5冊しかの本 was incorrect, it seems the correct answer is 5冊しか本. Is this a separate usage which isn't listed above? I couldn't find any specific information about it.
It's hard to say without seeing the full sentence, but I imagine it was something like the following from the site's library: 私は、10冊しか本を持っていない。 (I have no more than ten books) If that's the case, this falls under the first usage.
It's easier to understand if you think of しか as describing the action/verb. For instance in 一枚しか作文を書きませんでした (I've only written one page of the essay) from above, "one page" describes how much I've written, not the essay itself, so 一枚しかの作文 would be wrong. Likewise, in 彼しか事実を知らない (only he knows the truth), "he" describes who knows and not some aspect of the truth, so 彼しかの事実 would also be wrong. I hope this somewhat helped clear up the confusion.
I wouldn't say it's quite similar to だけ. The way I think of them is that だけ means "only", without any suggestion that it is a smaller than expected/normal amount.
You are right in that only that option exists, so one is "stuck to it" - but this only applies to しか.