环

• A boolean ring is absolutely flat .
  布尔环是绝对平坦的。
• The country is encircled by the sea .
  这个国家四面环海。
• Pick up both loops, and bring hands together, please .
  请拿起两个套环，合拢双手。
• This invasion was planned, it was efficient .
  打登陆战，都有严密的部署，环环紧扣。
• Thus for a torus many new circumstances arise .
  对于一个环管就有许多新的情形发生。
• He had used a coat hanger to break a seal on the catch .
  他用衣架砸断了封住的锁环。
• In-side there is a hollow ring .
  里面有一个中空的环。
• The pylorus may be palpated as a thick ring of muscle .
  可触诊出幽门是增厚的肌肉环。
• a ring homomorphism f: a→b is finite.
  环同态f：AB叫做有限型的。
• Treatment with butyllithium gave rise to cyclopropanes .
  用丁基锂处理，即得到环丙烷。