1． 被动式：现在分词被动式由"being＋过去分词"构成，如：
　The machine being repaired is from a European country.
　Bob saw Mary being attacked.
　Being written in haste, the letter was difficult to read.

2． 完成式和完成被动式：现在分词完成式主要用在状语中，表示分词动作在谓语动作之前
　发生，如果是被动动作时，则用完成被动式，分别由"having＋过去分词"和"having
　been＋过去分词"构成，如：
　　Having failed to qualify as a teacher, he turned to business.
　　The decision having been made, the next step was how to raise money.
　　Having been desalted（脱盐）, sea water can be used for various purposes.