Because the Klingon verb in this sentence does not have an aspect suffix indicating continuous aspect (-ing).
In general, translate Klingon verbs without an aspect suffix into simple tenses in English (Mara sleeps, Mara slept, Mara will sleep); Klingon verbs with a continuous suffix (-taH, -lI') into continuous tenses in English (e.g. Mara is sleeping) and Klingon verbs with a perfective suffix (-pu', -ta') into perfect tenses in English (e.g. Mara had slept).
The correspondence is not exact but that's what we use on this course.
The various aspect suffixes will be taught later, but for now, keep to simple tenses in English for translations.
If present simple seems too odd without context, the past tense should always be accepted, e.g. you could answer "Mara slept" instead of "Mara sleeps".