时态/语态 主动 被动
一般式 doing being done
完成式 having done having been done
否定式 否定词（not/never） +分词
Knowing his uncle would come, he began to make some preparations.
新概念英语视频2. 现在分词的完成形式主要用在状语中，表示动作在谓语动作之前发生。 Having been there many times, he offered to be our guide.到哪过许多次，他主动担任向导。 The delegates, having fulfilled their mission, arrived back in Shanghai.代表团完成使命后，返回上海。注：在独立结构中，也可以用现在分词的完成形式。3. 在表示一个被动的动作时，如果这个动作是现刻正在进行的，或是与谓语表示的动作同时发生的，就可以用现在分词的（完成）被动形式。这种形式可以作定语、状语或构成复合宾语。 That building being repaired is our library. 正在维修的建筑物是我们的图书馆。If you are a fan of J．K Rowling and her Harry Potter book series, you may be fascinated with the idea of an invisible coat．You are not alone．Scientists have been working hard to produce a material which will make buildings as well as people invisible．Now a Canadian company claims to have succeeded with magical textile （纺织品） called "Quantum Stealth"．British Columbia based on Hyperstealth Technology Corporation claims that the material makes its wearers completely invisible, even to people with night glasses．Also, just like the young wizard's coat, it is light-weight and does not need cameras, batteries, lights or mirrors to operate．But best of all, it is cheap to make．As to how it really works, the company keeps it a top secret．Besides stating that they have successfully managed to bend light waves, so that they go round the material instead of through it, the company is not giving out any details．What it does detail is all the good uses that Quantum Stealth could be put to-ranging from protecting US and Canadian soldiers forced to step into enemy region, to allowing special armed forces to carry out surprise attack without any fear of being seen．And if that is not enough they even imagine creating aircrafts and submarines （潜水艇） that can go completely undetected．To prove that Quantum Stealth really exists, the company has released photos and even a video showing its magical properties．For those that are still sceptical, they have only one thing to say both the US and Canadian military officials have witnessed it live and are so impressed that they are working with Hyper stealth Technology to create the next generation "survival blanket" that could make the soldier invisible all at once! If this is indeed true, we have only one question: When will this magical fabric be available to the rest of us?44．What’s the purpose of the first paragraph?A．To bring in the topic．B．To draw peopled attention to J．K Rowling and her idea．C．To make the article interesting．D．To introduce the Canadian company．45．According to the passage, Quantum Stealth is _____．A．an invisible coat worn by the wizard in the film "Harry Potter"B．a type of material making its users invisibleC．an equipment employed as an alternative for camerasD．an advanced weapon used to attack enemies46．Which of the following words can be used to describe the coat?A．Convenient but not expensive． B．Creative but heavy．C．Ordinary and light． D．Magical and imaginary．