Да-constructions: no infinitive

Bulgarian has no infinitive. Where English says to swim or to come, Bulgarian uses да + a normally conjugated present-tense verb. Verbs like искам (want), мога (can), трябва (must), обичам (love, like), започвам (begin) and спирам (stop) are followed by such a да-clause.

• Same subject: both verbs take the same person. Можеш ли да плуваш? (Can you swim?) Ние обичаме да готвим. (We love cooking.)
• Трябва never changes: Ти трябва да учиш. (You must study.)
• Different subject: the verb after да takes the new person. Искам и ти да дойдеш. (I want you to come too.)

Never leave out да: not *Искам купя, but Искам да купя. (I want to buy.)