Non-Human Plurals Take Feminine Singular

In Arabic, a plural that refers to things, animals or ideas (non-human) is treated as feminine singular. Everything that agrees with it takes the feminine singular form:

• adjective: السيارات جديدة (the cars are new)
• demonstrative: هذه الأسئلة (these questions), تلك الجبال (those mountains)
• pronoun هي and relative pronoun التي
• verb: الرسائل وصلت and وصلت الرسائل (the letters arrived)

The verb is feminine singular in both word orders.

Plurals of people behave differently: after the noun, adjectives and verbs are plural (الطلاب مجتهدون, المسافرون وصلوا, البنات سريعات), and you use هؤلاء, هم and الذين. A verb that comes before its subject stays singular even for people: وصل المسافرون.