"There are many chapters."

Translation: Multae lectiones sunt.

[lunalui]

There is a problem here. There is no "multae" option (feminine, as lectio) in the words bank, but only "multi". I wrote the correct solution exactly as it appears above here using the keyboard, but my correct answer was marked wrong, while the given answer was "multi lectiones sunt" (I have a screenshot to prove it)

[Brandon640296]

Why would it mark "Multi lectiones sunt" incorrect, and how do I know when to use -i vs -ae?

[lunalui]

Lectio/lectionis is feminine so you need to inflect multus accordingly

[N_Dunlap]

Are there any general rules to determine which one to use or do you just need to learn case by case?

[lunalui]

There are no rules that work all the time. That's especially true for the third declension and the fourth one.

Otherwise, names of the first declension are for the most part feminine, but there are exceptions (poeta, pirata, agricola,... are masculine; there are no neutrals). Names of the second declension with nominative in -us tend to be masculine, but again there are exceptions (names of plants like fagus, quercus, malus,... are feminine, and virus is neutral); on the other hand those ending in -er are all masculine and only neutrals have a nominative in -um. As for the fifth declension, all names but dies and its composits (which are masculine) are feminine.

I hope that answers.

[JosOjeda16]

I got a problem. I wrote "Multa capitula sunt". It's the neutral of the second declination: "Capitulum", with the plural nominative in "Capitula". It should be right, but it's wrong.