I'm not familiar with the Michel Thomas Method, but I'm sure it wouldn't hurt you to read up on conjugations. he
, has
, ha
, han
, and hemos
are not prefixes by any stretch of the imagination. Each are the present indicative conjugation of the verb haber
.
Haber
is an (nearly always) auxiliary verb (helping verb). This is the verb that allows us to create perfect conjugations. We use them in English a lot and sometimes you would wonder how we ourselves interpret their use.
Is "haber" always a helping verb?
If I had had twelve dollars I would have bought it.
translates to
Su hubiera tenido doce dólares lo habría comprado.
The first bolded conjugation is called Past Subjunctive while the second is called Conditional
The way haber works (as an auxiliary verb) is this
(conjugated form of haber) + (past participle) = to have (past participle)
He has eaten = Él ha comido
We have finished = Hemos terminado.
Depending on which of the three kinds of verbs your verb is, you will either have -ado or -ido to express the past participle.
Verbs that end with an -ar
generally switch to -ado
Verbs that end with an -er
or -ir
generally switch to -ido
The same goes for the other part of your question
-Ar
verbs have an imperfect past tense that ends with -aba
-Er
and -Ir
verbs have an imperfect past tense that ends with -ía
.