Choose the appropriate prepositions for the given sentence:
It was ____ midnight when three cars dropped ____ the passengers and disappeared.

During is used to talk about something happening within a time period.
On is used while referring to days and dates.
In is used while referring to months, centuries, years and long periods.
Around means nearly at.
So, the most suitable preposition for the first blank is 'around'.
The second blank should use 'off' as 'dropped off' is the most suitable phrase according to the sentence.
drop off means to take someone or something, esp. by car, to a particular place.

Correct sentence: It was around midnight when three cars dropped off the passengers and disappeared.