Breakdown of Пациенты сидят в приёмной, покачивают ногами и посматривают на дверь.
и
and
дверь
door
в
in / to (direction)
на
on, at / by (transport) / to (a place) / to (in answer to)
Questions & Answers about Пациенты сидят в приёмной, покачивают ногами и посматривают на дверь.
Both покачивают and посматривают have the prefix по- and suffix -ива-. What does this combination do to the meaning?
This specific combination (a circumfix) creates an "intermittent-attenuative" verb. It shows that an action happens from time to time (intermittent) and with low intensity (attenuative). Instead of continuously swinging (качают) and staring (смотрят), the patients are lightly swinging their legs from time to time and periodically throwing glances.
Why is ногами in the instrumental case here? They are swinging their legs, which sounds like a direct object.
In Russian, verbs describing the physical movement or gesturing of body parts—like swinging legs, nodding a head, or waving hands—require the instrumental case rather than the accusative. Even with the modified verb покачивают, this rule still applies.
Why does the noun for "waiting room", приёмной, have an adjective ending?
Приёмная is a substantivized adjective—an adjective that acts as a noun. It originally comes from the phrase приёмная комната (reception room). Because of this, it declines exactly like a regular feminine adjective, which is why it takes the feminine prepositional ending -ой here.
Why is it на дверь and not just дверь or another preposition?