从句

• Noun clauses that start with question words , whether and if
  以whether （是否）和if （如果）引导的名词性从句
• The bike which had been stolen belongs to jack
  过去分词或过去分词短语作定语时，其功能相当于一个定语从句。
• Non - defining relative clauses . noun clauses introduced by " it "
  非限制性从句；以it （它）做主语的名词性从句
• Adverbial clause of real condition
  真实条件状语从句