الطَّرِيقُ قَصِيرٌ، لَكِنَّ السَّفَرَ مُتْعِبٌ
Translation: The route is short, but the journey is tiring.
«الطَّرِيقُ قَصِيرٌ»: initial nominal sentence. «لَكِنَّ»: corrective/contrastive particle. «السَّفَرَ»: accusative ism lakinna; «مُتْعِبٌ»: nominative khabar.
The meaning of contrast is added; the case rule stays the same.