-in/-hin

The -in/-hin pattern is one of three main object-focus affixes and follows specific spelling and sound rules. This basic neutral verb form (infinitive) is also the exact form used to give commands or imperatives (e.g., Basahin mo ito. - Read this.).

• -in: Used for roots ending in a consonant (e.g., alis + -in = alisin). This includes words ending in a glottal stop (impit), because the glottal stop is considered a consonant in Filipino phonology. However, standard Tagalog writing does not write the glottal stop, so you must rely on the word's pronunciation to choose between -in and -hin. For example, sira (broken/destroy, pronounced with a final glottal stop) becomes sirain.
• -hin: Used for roots ending in a vowel (e.g., basa + -hin = basahin).

Important Sound Changes:
1. Stress Shift: The emphasis usually shifts one syllable to the right (e.g., bása becomes basáhin).
2. Vowel Dropping (Syncope): Some common verbs drop their last vowel when adding the suffix. For example, bili (buy) becomes bilhin, dala (carry) becomes dalhin, gawa (make) becomes gawin, and the highly frequent irregular verb kuha (get/take) becomes kunin (which undergoes both vowel dropping and a consonant change).
3. D to R Change: When a root word ends in 'd', it often changes to 'r' when the suffix is added. For example, lakad (walk) becomes lakarin.
4. O to U Change: When a root word ends in 'o', it almost always changes to 'u' when a suffix is added. For example, luto + -in = lutuin.

Aspect Changes:
Crucially, the -in/-hin suffix disappears in the completed aspect and progressive aspect. It is replaced by the infix -in-, which is inserted right before the first vowel of the root word. For example, basahin becomes binasa (not binasahin) in the completed aspect, and the progressive aspect becomes binabasa (is reading), combining the infix and reduplication while dropping the suffix. For roots starting with a vowel, the -in- infix acts as a prefix for the completed aspect (e.g., alis becomes inalis; isip becomes inisip), and the progressive aspect uses in- as a prefix alongside reduplication (e.g., alisin becomes inaalis). For roots starting with L, R, W, or Y, the infix becomes the prefix ni- (e.g., luto becomes niluto, not linuto). For the contemplated aspect (future), the first syllable of the root is reduplicated and the suffix is retained (e.g., babasahin).

Unlike English, where the 'passive voice' is often avoided, the object-focus in Filipino is the standard, natural way to speak when the object is specific (e.g., 'Read the book' vs 'Read a book').