Breakdown of Het is duidelijk dat hij heel slim is.
zijn
to be
hij
he / it (referring to a 'de'-word)
heel
very
het
it
Questions & Answers about Het is duidelijk dat hij heel slim is.
Why is the second is at the very end of the sentence?
The word dat (that) is a subordinating conjunction. When you use dat to connect two parts of a sentence, it forces the verb in that specific part of the sentence to the very end. That is why it is dat hij heel slim is instead of dat hij is heel slim.
In English, we can just say "It is clear he is very smart" and leave out "that". Can I drop dat in Dutch too?
No, you cannot drop dat in Dutch. While English often leaves out the word "that", Dutch strictly requires it to connect the two sentence parts. You must always use it here: Het is duidelijk dat....
Why doesn't the verb move to the end in the first part (Het is duidelijk)?
Het is duidelijk is the main clause (the core part of the sentence that can stand on its own). Main clauses follow the normal Subject-Verb word order. The verb-at-the-end rule only applies to the sub-clause introduced by dat.
Doesn't heel usually mean "whole"?
It can! Heel means "whole" when describing a noun (like een heel brood for "a whole loaf of bread"). However, when you put it directly in front of an adjective like slim (smart), it acts as an adverb meaning "very". You could also say erg slim here, which means the exact same thing.