A solar year, the time it takes the Earth to complete one revolution of the Sun (between 365.24 and 365.26 days depending on the point of reference)

(a duration of) one year / an unspecified year in the past

(idiomatic) to age, to get older

three years; the third year / (education) the third school year / (figuratively) a long period of time, several years

three years; triennial / three years old

It's difficult to make a life

is the best among (others)

loyalty

inmost, inside / heart, mind (also 心)

(formal) dear sirs, Messrs. (form of address used in formal letters, placed after the name of the organization to address members of that organization)