Language/Spanish/Grammar/Use-the-letters-V-and-B

• All words in which this letter goes before another consonant are written with "b".

Examples: libro, amable, subterráneo, obsequio.

• Before "m" and "p" is written "b", and after "n", "d" and "b" write "v".

Examples: embajador, empezar, enviar, adversario, subvención.

• Words that begin or end with "bio" are written with "b".

Examples: biografía, biología, anfibio.

• Words ending with "bilidad" are written with "b", except: "movilidad" - "civilidad".

Examples: responsabilidad, amabilidad.

• They are written with "b" the terminations of the past imperfect indicative of the verbs of the 1st conjugation and also preterite imperfect indicative of the verb "ir".

Examples: amábamos, cantabáis, alzaba, iba, ibas, íbamos.

• All the compound words of the verb "venir" are written with "v".

Examples: convenir, prevenir.