学弟 junior male schoolmate。
学妹 junior female schoolmate。
junior|ˈdʒu:niə(r)|[常用于名词前] ~ (to sb) having a low rank in an organization or a profession 地位（或职位、级别）低下的。
例句：
1、 Come on, Junior, time for bed.
2、He is junior to me by a year.
3、Discontent among junior ranks was rapidly spreading.
4、There are several people junior to me .
5、An ensign is a junior officer in the United States Navy.
扩展资料：
|meɪl|(abbr. m) belonging to the sex that does not give birth to babies;connected with this sex 男性的；雄性的；男的。
例句：
1、Male workers were made permanently sterile by this pesticide.
2、These clubs are the last bastions of male privilege.
3、The male bird performs a sort of mating dance before copulating with the female.
4、The male has beautiful tail feathers.
5、The male ape defends his females from other males.
female|ˈfi:meɪl|being a woman or a girl 女的；女性的。
例句：
1、The female of the species is more deadly than the male.
2、The female changes colour during the breeding season.
3、 He thought I was being a hysterical female.
4、The commentators make endless quips about the female players' appearance.
5、The contract gives a female executive maternity leave rights.
schoolmate|ˈsku:lmeɪt|A schoolmate is a child who goes to the same school as you, especially one who is your friend.(尤指关系要好的)同学，同窗，校友。
例句：
1、When his schoolmate made the last goal, the boy gave out with an untrammeled yell.
2、She ran against an old schoolmate in the park last week.
3、He started the magazine with a schoolmate.
4、 I paired off with an old schoolmate of mine.
5、The Phinneys-the parents of his schoolmate Tad-were very sporting about turning their house into an armed camp for the night.
词汇英文翻译：
学弟
junior male schoolmate
学妹
junior female schoolmate
词汇解释：
junior
|ˈdʒu:niə(r)|
[常用于名词前] ~ (to sb) having a low rank in an organization or a profession
地位（或职位、级别）低下的
male
|meɪl|
(abbr. m) belonging to the sex that does not give birth to babies; connected with this sex
男性的；雄性的；男的
female
|ˈfi:meɪl|
being a woman or a girl
女的；女性的
schoolmate
|ˈsku:lmeɪt|
A schoolmate is a child who goes to the same school as you, especially one who is your friend.
(尤指关系要好的)同学，同窗，校友
学弟 junior male schoolmate
学妹 junior female schoolmate
junior|ˈdʒu:niə(r)|[常用于名词前] ~ (to sb) having a low rank in an organization or a profession 地位（或职位、级别）低下的
male|meɪl|(abbr. m) belonging to the sex that does not give birth to babies;connected with this sex 男性的；雄性的；男的
female|ˈfi:meɪl|being a woman or a girl 女的；女性的
schoolmate|ˈsku:lmeɪt|A schoolmate is a child who goes to the same school as you, especially one who is your friend.(尤指关系要好的)同学，同窗，校友
先辈せんぱい
senpai
森派
学妹和学弟都是
后辈こうはい
kouhai
扩害
分别用了日语当用汉字,平假名,罗马音和中文注音了啊
老师（