Learn Arabic (Modern Standard): تتراوح درجة الحرارة بين عشرين وثلاثين درجة. - The temperature ranges between twenty and thirty degrees.

تتراوح is a Form VI verb from the root ر و ح. Form VI verbs often describe continuous, gradual, or reciprocal actions. Here, it perfectly captures the idea of the temperature fluctuating or going back and forth between two points.

Why do we use عشرين and ثلاثين instead of عشرون and ثلاثون?

In Arabic, decade numbers (20, 30, 40, etc.) change their endings based on their grammatical role, behaving like regular masculine plurals. Because they follow the preposition بين (between), they are forced into the genitive case, which takes the -ين (-iin) ending instead of the nominative -ون (-uun).

The English translation says 'thirty degrees' (plural), so why is the Arabic word درجة singular?

This is a strict rule for Arabic numbers: the counted noun following any number from 11 to 99 must always be singular. It also takes the accusative case (known as tamyeez or specification), so it would be pronounced درجةً (darajatan) if you were reading with full vowel endings.

How do we structure the range 'between twenty and thirty' in Arabic compared to English?

To express a range, Arabic uses بين (between) followed by the first value, then simply و (and) followed by the second value. English speakers often make the mistake of trying to insert words like 'to' (إلى) here to say 'between twenty TO thirty', but Arabic strictly uses the 'between X AND Y' structure.