There are few questions words Why: “Wieso”, “weshalb” and “warum”.
Warum ist John in Paris?
We usually answer these questions with a main clause, followed by a causal clause using “weil”. The subordinate clause contains the reason for the information in the main clause.
If the main clause is a declarative clause, the verb takes position 2. The subordinate clause starts with the conjunction “weil”. In the subordinate clause, the verb always comes at the end.
John ist in Paris, weil er Paris liebt.
If the subordinate clause has two verbs (e.g., modal verb + infinitive, or perfect constructions with “haben/sein” + past participle), the conjugated verb comes right at the end. The non-conjugated verb (e.g., infinitive or participle) comes before the conjugated verb.
Ich kann nicht gut sehen, weil ich meine Brille habe lassen fallen.
