Special features

Modal verbs dürfen, können, mögen, müssen, sollen and wollen govern the infinitive of a full verb and can have no additional complements (e.g. an object). The infinitive that is connected to a modal verb is not preceded by the word zu.

Modal verbs can be combined with other modal verbs.

A modal verb can be connected with an infinitive only if the subject of the modal verb is the subject of the infinitive.

Modal verbs can also function as full verbs; in this case, they are not connected to an infinitive but to adverbial phrases that denote direction (same for all modal verbs) or to an accusative object (modal verbs wollen, mögen, ich möchte and können). These sentences are usually elliptical and the infinitive is not mentioned, because its meaning derives from context.

Modal verbs wollen and ich möchte can govern a dass-clause. In this case, the subject of wollen / ich möchte is not the same as the subject of the dass-clause. Dass-clauses with passive voice or modal verb structures are the exception to this rule.

Modal verbs form the present perfect and the past perfect tenses with the auxiliary verb haben + infinitive, instead of the past participle (Partizip II).

However, when modal verbs function as full verbs (i.e not connected to an infinitive), they form the present perfect and the past perfect with the past participle (Partizip II).

Furthermore, modal verbs do not:

1. form the imperative mood

2. form the passive voice. However, they can govern a passive infinitive.