-ちゅう【-中】 (-ch)
  1 〔…の中〕 in…; 〔範囲内〕 within…; 〔なかでも〕 among…; of….
  30 人中の一人に選ばれる　be selected as one of (the) thirty
  ･十中八九　⇒じっちゅうはっく
  ･空気中に含まれる酸素の量　the amount of oxygen in the air.
  それは不幸中の幸いだった.　It was one consolation in the midst of misfortune.
  ･彼はエリート中のエリートだ.　He is the elite of the elite.
  2 〔…の間(に)〕 during…; in (the course of)…; through…; throughout…; while…; 〔進行中〕 under…; in the process [course] of…; in progress.
  不在中に　during [in] one's absence; while one is away [out]
  ･午前中に[ずっと]　in [all through, throughout] the morning
  ･建築中の家　a house under construction [being built].
  授業中いつも寝ている.　He's always sleeping during class.
  ･その件はただ今交渉中です.　The matter is now under negotiation.
  ･来月中にはできあがるだろう.　It will probably be completed next month.
  ･水泳中におぼれて死んだ.　He was drowned while swimming.
  ･今試験中です.　The examinations are going on now.
  ･部長は今会議中です.　The department chief is in a meeting now.
  ･何度かけても話し中だった.　I tried several times but the number was always busy.
  ･〔道路の掲示で〕 200 メートル先工事中.　Construction 200 meters ahead.