是……的: stating a view or attitude (这个问题是可以解决的)
【四42】特殊句型 / special sentence patterns
Tone colorsā tone 1á tone 2ǎ tone 3à tone 4a neutral
This 是……的 does not pin down the circumstances of a past event (我是昨天来的, hsk3-g01): it gives a judgement a firm, settled tone. It speaks about a general truth or the future, never about a finished event: 这个问题是可以解决的 (this problem can be solved, no doubt about it).
Between 是 and 的 you usually find a modal verb (会, 能, 可以, 应该), an adverb (一定, 绝对, 很) or an adjective: 那样的事情是绝对不会发生的; 这道题是很简单的. The effect is "trust me, that's how it is": you reassure, assert or calmly explain your view.
In speech 是 can drop (这个问题可以解决的), but 的 stays, because it closes the sentence. Do not mix it up with 了, which reports a change, or with the 是……的 of hsk3-g01, which highlights a detail (when? where? how?) of a past event.
Examples
这个问题是可以解决的。
Zhège wèntí shì kěyǐ jiějué de.This problem can be solved, no doubt about it.
你放心，他是会来的。
Nǐ fàngxīn, tā shì huì lái de.Don't worry, he will come.
这道题是很简单的，你再想想。
Zhè dào tí shì hěn jiǎndān de, nǐ zài xiǎngxiang.This question is really simple, think about it again.
只要努力，你是一定能成功的。
Zhǐyào nǔlì, nǐ shì yídìng néng chénggōng de.As long as you work hard, you will certainly succeed.
这样做是不对的，我们应该先问问他。
Zhèyàng zuò shì bú duì de, wǒmen yīnggāi xiān wènwen tā.It's wrong to do it this way; we should ask him first.
那样的事情是绝对不会发生的。
Nàyàng de shìqing shì juéduì bú huì fāshēng de.Something like that will never happen.
Common mistakes
✗ 这个问题是解决的。 → ✓ 这个问题是可以解决的。(to state a view you need a modal or an adverb between 是 and 的).
✗ 他是不会来了。 → ✓ 他是不会来的。(the sentence closes with 的, which asserts; 了 would report a change).