"Their children are reading."
Translation:Leurs enfants lisent.
conjugation of verb être: je suis, tu es, il/elle/on est, nous sommes, vous êtes, ils/elles sont. therefore "es" is only when subject is "tu".
In English, to mean that an action is in progress at the time you speak, you use the continuous verbal form, ie verb BE + action verb in the gerund form (-ing). o they are reading means they currently read In French, this verbal form does not exist (directly translated “ils sont lisant” is incorrect).
Therefore, you can translate either “ils lisent” or “il sont en train de lire”, where the construction verb être + en train de + infinitive correctly expresses the English continuous form.
Remember that in French, possessive adjectives agree with the object and not the owner. So, with "enfants" (plural), you need "leurs" (plural).
if you mean that the couple have only one child, you say "leur enfant".
to distinguish the plural form from the singular form, in oral, you will liaise "leurs-Z-enfants".
ils sont lisent = they are read - it does not work either in French, or in English
"eating" is the gerund form of "eat" but the French language does not use that verbal form to express a continous action.
so "they are eating" = ils mangent (simple present = they eat) or ils sont en train de manger (equivalent to: they are in the process of eating)
The French language is very strict when it comes to singular and plural.
"Leur" and "leurs" are used exclusively when there are 2 owners or more.
"Leur enfant" = their child
"Leurs enfants" = their children
On this course, Duolingo does not accept "their" when there is one owner.