Breakdown of Trafikljuset som vi tittar på är belyst.
vara
to be
vi
we
titta på
to look at
som
who / which / that (relative pronoun)
Questions & Answers about Trafikljuset som vi tittar på är belyst.
Why is the past participle belyst instead of belysad?
The verb is belysa (to illuminate), which belongs to Group 2. Group 1 verbs take -ad, but Group 2 verbs form their past participles by adding -d or -t. Because the stem belys- ends in an s (a hard, voiceless sound, just like k or p), it takes a -t, making the base past participle belyst.
Does belyst need an extra -t to agree with the ett word trafikljuset?
No, it doesn't need an extra one! Because the base past participle for this specific Group 2 verb already ends in -t (as in en belyst skylt), the ett form stays exactly the same (ett belyst trafikljus). If the subject were plural, you would add an -a to make it belysta.
Why are the words på and är right next to each other in the middle of the sentence?
It happens because som vi tittar på (that we are looking at) is a relative clause describing Trafikljuset. The Swedish verb phrase is tittar på (to look at). Just like in English, the preposition på stays at the very end of that descriptive clause, right before the main sentence resumes with the verb är.