They have just arrived.

Present Perfect Tense

This sentence uses the Present Perfect tense ('have arrived'). This tense is used to describe an action that has recently happened, often with the adverb 'just'. It emphasizes the recency of the action and its relevance to the present moment.

Explanation: 'Have arrived' is the Present Perfect form. 'Just' is an adverb that indicates the action happened very recently. The Present Perfect connects the recent past event (arrival) to the present situation.