The perfect tense needs an auxiliary verb.

 The perfect tense needs an auxiliary verb.

But which one – 𝗵𝗮𝗯𝗲𝗻 or 𝘀𝗲𝗶𝗻? Here is the rule that covers the vast majority of cases: 𝗦𝗘𝗜𝗡 – for two categories only: 𝟭. Change of location (Movement from A to B): gehen, kommen, fahren, fliegen, reisen, laufen Ich bin nach Berlin gefahren. (I drove to Berlin.) 𝟮. Change of state (Transition): werden, sterben, einschlafen, aufwachsen Er ist eingeschlafen. (He fell asleep.) 𝗛𝗔𝗕𝗘𝗡 – for everything else. 𝟭. Transitive verbs (verbs with an object): Ich habe einen Apfel gegessen. 𝟮. Static verbs / No change of state: Sie hat viel gearbeitet. The test – two questions: Is it a movement from one place to another? Is it a change from one state to another? Yes to either? 𝘀𝗲𝗶𝗻. No to both? 𝗵𝗮𝗯𝗲𝗻. This covers the overwhelming majority of sentences you will build at A2 and B1.