The Sentence (جملة/مركّب مفيد ) A sentence is a group of...

جُملةٌ إنشاﺋِﻴَّﺔٌ : is the جُمله whose meaning does not support the possibility of truth and falsehood e.g. هل عِندَكَ قَلَمٌ (Do you have a pen?), إشرَب الماء (Drink the water!). A sentence, essentially, is the conveyance in words of a specific linkage made between two ‘ideas’; one primary, the other descriptive within the mind of the speaker. Now if the two ideas also exist in the outside world and what the speaker is saying corresponds to the outer reality, it is termed true.

If it does not correspond it is called false. For instance the sentence زَيدٌ ناﺋِﻢٌ ( زَيدٌ is sleeping) in which the idea of sleeping has been linked affirmatively to زَيدٌ can be verified by judging it with the reality. When looking towards what exists in the world, if we see زَيدٌ is actually sleeping, it would mean the affirmation is correct, and hence the statement is true. Otherwise, it would be false. In a **جُملةٌ إنشاﺋِﻴَّﺔ no such external reality exists.

It is the words of the speaker which for the first time are bringing the two ideas together. ** إنشاء literally means to originate. Now we see clearly why sentences such as questions and commands do not support truth and falsehood; confirmation and non-confirmation to external reality can not occur due to there being no such reality.