Professor Nilson Alves explains the conjugation rules for derived verbs, using the verbs 'deter' and 'intervir' as examples.
The first piece of advice is that the verb 'intervir' does not originate from the verb 'ver'. Consequently, it is incorrect to use the form 'interviu'. If the base verb is 'vir', the prefix 'inter' must be maintained, and the root conjugated, for example, 'eu venho'. In this case, it is correct to say 'eu intervenho', not 'interviu'. An example is the phrase 'Ele veio', which transforms into 'O governo interveio'. The form 'interviu' is absent in standard language culture; instead, it is correct to use 'os governos intervieram', excluding the option 'interviram'.
Similar rules apply to the verb 'deter'. Often in spoken language, one might hear the expression 'ele deteu', but the correct form should be built from the verb 'ter'. For instance, if 'eu tenho' is used, the correct form is 'eu detenho'; and if 'eu tive' is used, one should use 'eu detive'.



