是由

• Laws don't all come from the same quarter .
  法律不全是由一个长官制定出来的。
• It is formed by a process of "self-ionization" .
  ”它是由“自身电离”生成的。
• A great deal of frontier humour was oral .
  边疆幽默有一大部分是由口头传述的。
• Her baby was delivered by her own doctor .
  她的婴儿是由她自己的医生给接生的。
• He was brought up by his grandmother .
  他是由他奶奶带大的。
• The meeting was sponsored by 22 colleges .
  这次会议是由二十二所院校发起的。
• Gaskets and o rings are made of elastomers .
  密封垫和O型环是由人造橡胶制成的。
• Water is composed of the elements hydrogen and oxygen .
  水是由氢、氧元素组成的。
• I always stay with him when he has to be in .
  每次他不得不住院时，是由我陪着他。
• Limestone is rock composed of calcium carbonate .
  石灰石是由碳酸钙所构成的岩石。