In your sentences, the following verb tenses were used:

eu imaginava = pretérito imperfeito do indicativo

ela passaria = futuro do pretérito do indicativo (presente do condicional)

ela passasse = pretérito imperfeito do subjuntivo

In formal Portuguese, the following verb tense correlations are indicated:

eu imaginei = pretérito perfeito do indicativo

ela tivesse passado = pretérito mais-que-perfeito composto do subjuntivo

So the correct sentences would be:

I suggest you read the following article to learn more about verb tense correlation:

And the following website to look up verb conjugations (which is sometimes tricky even for native speakers):