Questions & Answers about Danas radim više nego juče.
Radim already means I work / I am working. The ending -im shows 1st person singular (I), so Serbian usually does not need the pronoun ja.
- Radim = I work / I’m working
- Ja radim = I work / I’m working, but with extra emphasis on I
Also, sam is not used with ordinary present-tense verbs like radim.
Sam is an auxiliary used in forms like the past tense:
- Radio sam = I worked
So in this sentence, Danas radim više nego juče, radim by itself is exactly right.
Radim is in the present tense.
In Serbian, the present tense can often translate into English in more than one way, depending on context:
- radim = I work
- radim = I am working
So Danas radim više nego juče can naturally mean:
- Today I work more than yesterday
- Today I am working more than yesterday
- Today I’m working more than I did yesterday
The exact English version depends on the situation, but the Serbian sentence is completely natural.