Ability (can ~)

② Nepali grammar rules

1. Infinitive -न + सक्नु

Use पढ्न सक्छु (I can read) / गर्न सक्छु (I can do it) / जान सक्छु (I can go) for ability/possibility.
The preceding verb is the -न infinitive, such as पढ्न, not unchanged dictionary पढ्नु.

2. Conjugate सक्नु

Compare म गर्न सक्छु (I can do it) / हामी गर्न सक्छौं (we can do it) / उहाँ गर्न सक्नुहुन्छ (he/she can do it, respectful).
Keep गर्न while conjugating the final सक्नु for person/respect; do not combine two finite presents such as गर्छु सक्छु (incorrect combination; use गर्न सक्छु for ability).

3. Negative and past ability

Compare सक्छु→सक्दिनँ, past सकेँ, and negative past सकिनँ.
Respectful forms include सक्नुहुन्न/सक्नुभयो/सक्नुभएन.
Keep the preceding action in the -न form.

4. Ability versus learned know-how

नेपाली बोल्न सक्छु (I can speak Nepali) expresses ability; नेपाली बोल्न जान्छु (I know how to speak Nepali) emphasizes learned know-how. जान्नु means know and जानु go; the same-looking finite जान्छु must be interpreted in its construction.

5. Can, may and want

जान सक्छु (I can go) expresses ability, जान हुन्छ? (it is permissible to go) asks permission, and जान मन पर्छ (want/like to go, depending on context) expresses a desire.
Ability does not entail permission.
See topic 31 for epistemic possibility with हुन सक्छ (may be; can be).

A reference table for comparing personal forms

Negate सक्नु to say cannot.