闰年的英文：
leap year
bissextile

闰年是为了弥补因人为历法规定造成的年度天数与地球实际公转周期的时间差而设立的。补上时间差的年份为闰年。闰年共有366天。

This year is a leap year.
今年是闰年。

Leap year recurs every four years.
每四年闰年一次。

The leap year comes around once in four years
闰年每4年再现一次。

Leap-year day(every four years) and year-end day(every year) would be counted as extra Saturdays.
人们把闰年日(每四年一天)和年末日(每年一天)视为外加的星期六。

A leap year occurs once every four years.
每四年才有一次闰年。

Year succeeds to year.
年复一年。

This year is a banner year for crops.
今年是个丰年。

Year after year went past.
一年又一年过去了。