Here there is just one imperfect and matā asks a time question. Tusāfiru stays indicative; it is not a jussive conditional verb.
Book example: مَتَى تُسَافِرُ؟
When will you travel?
Matā: interrogative time adverb in the accusative adverbial position; tusāfiru: indicative imperfect with implicit “you”.
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Indeclinable Adverbs — Ghāyāt, Time and Place
Here there is just one imperfect and matā asks a time question. Tusāfiru stays indicative; it is not a jussive conditional verb.
Book example: مَتَى تُسَافِرُ؟
When will you travel?
Matā: interrogative time adverb in the accusative adverbial position; tusāfiru: indicative imperfect with implicit “you”.