abbr.birth control 计划生育，between centers 中心距，back course （返）回（航）程，back-cross 回交...

BC的音标：...

The brooch dates back to the fourth century BC.这枚胸针的历史可以追溯到公元前4世纪。This play was first performed in 411 BC.该剧于公元前411年首演。born circa 150 BC生于约公元前150年...

There they remained until Cyrus took Babylon ( 538 BC ).他们一直留在那里,直到居留士攻占巴比伦 ( 公元前538年 ).Acupuncture was practised in China as long ago as the third millennium BC...中国早在公元前3,000年就已开始采用针灸疗法。By c . 1200 BC, they had crossed...