Questions & Answers about Jag ringde henne i går, men hon svarade inte.
Because hon is the subject form, while henne is the object form.
In this sentence, jag is the subject doing the action, and henne is the person receiving the action.
Compare:
- Hon ringde mig. = She called me.
- Jag ringde henne. = I called her.
So this works like English she / her:
- hon = she
- henne = her
They are both in the simple past (also called the preterite).
- ringa → ringde
- svara → svarade
So the past meaning is built directly into the verb. Swedish often does this where English also uses a simple past form, but Swedish does not need an extra helping verb.
A useful thing to notice is that different verbs form the past in different ways, so you have to learn each verb pattern:
- svara is a very regular -ade past verb
- ringa has the past form ringde