Translation:This is the worst project that I have seen!
The general rule is that "który" refers to sets of objects and "jaki" refers to features/attributes. E.g.:
- Jakie swetry ci się podobają? - Which kind of sweaters do you like? (general question)
- Które swetry ci się podobają? - Which sweaters do you like? (when talking about a known set of sweaters, for example in a store)
So, you need to know if the part of the sentence that comes after "jaki"/"który" refers to a set of objects or to a feature. Here, it refers to the feature of "having been seen by you". This is why you should choose "jaki".
You have to be one tired man by the time you go to bed. Or, do you sleep? You must answer questions all day. How many hours do you put in on this program a day?
That's a very good question... I guess 2 is the absolute minimum, on a not-busy day.
In another example jakiego is used instead of jaki: "To najdłuższy wąż, jakiego widziałem." Just wondering when to use each one, thanks
It's because of the object that is seen. "widzieć" takes Accusative, right? Remember how different would be "I see a project" (Widzę projekt) and "I see a snake" (Widzę węża). The first one is inanimate, so the Accusative form is identical to Nominative, the latter is animate, so it's identical to Genitive.
No, "that" can't be translated to "że" if it's used in place of "which".
I told you that you have to go - Powiedziałem ci, że musisz iść.
I have the tools that you need - Mam narzędzia, których potrzebujesz (note that that can be replaced by which)