to secretly try to discover information about a person, country, etc.

it is surprising because it is unusual or unexpected, so it is ...

to try to get or achieve something

coming from outside the planet Earth

it confuses you because you do not understand it, so it is ...

human society with its well developed social organisations, or the culture and way of life of a society or country at a particular period in time

something that exists or happens, usually something unusual

if there is a particular amount of time that remains

when something is obvious

something strange or unknown which has not yet been explained or understood

having no explanation

when you cannot find anyone and do not know where he / she is

if a ghost or ghosts appear in some place, this place is ...