He's my senior by three years.他比我大三岁。
The three vice-ministers are my seniors.三位副部长都是我的上级。
He was my senior at school.他是我上一届的学生。
The seniors are planning to have a gathering.这些毕业班学生计划聚会一次。

［同义词］ adj.  elder, older, superior n.  better, superior
［反义词］ adj.  junior, minor, younger n.  inferior
［词源］＜拉丁语senior(年长的,资格老的)

用作定语
▲～+n.
 She is a senior patient.她是一位高龄患者。
He is a senior member of the committee.他是一名资深的委员。
He's the company's senior employee.他是公司的高级雇员。
They are senior students.他们是高年级学生。
用作表语
▲S+be+～+prep.-phrase
 He is senior to me.他是我的上司。
Smith is senior to me by three years.史密斯比我大三岁。
▲S+be+～+to-v
He is too senior to try for cabinet office.他年事已高,不宜去谋求内阁部长的职位了。

下面三个句子的意思相同:
My brother is senior to me by two years.
My brother is my senior by two years.
My brother is two years senior to me.
我哥哥比我大两岁。