1）Owing to the fact that I had a lot of work to do, it wasn’t possible for me to accept their invitation.
改为下面的句子就简洁明了多了。I was too busy to accept their invitation.
2) My hometown is a quiet, peaceful place. It is quiet and peaceful because of the small number of people living there.
有时为了构成平行的句子结构或达到强调的目的，我们会重复使用某些词语。但是，无目的地重复会导致笨拙。可改为：My hometown is a quiet, peaceful place because of the small number of people.
I returned to my room. There was a note under my door. It was from Bob. He said he was in the town and looked for a job. He hadn't found anything yet. He added that he was sorry to have missed me.
When I returned to my room, I found a note from Bob under the door. He said he was in the town looking for a job, but hadn’t found anything yet. He added that he was sorry to have missed me.
(1) 既可以用主动式也可以用被动式, 例如:
例1：We use machines not only in industry but in other sectors of national economy as well.
Machines are widely used not only in industry but in other sectors of national economy as well.
(2) 既可以用肯定式也可以用否定式, 例如:
例1： I shall go there unless it rains.
I shall go there if it doesn't rain.
(3) 某些修饰成分既可以用在句子前面也可以用在后面, 还可以用在中间, 例如:
例1： In fact, speaking is one of the most important means of communication.
Speaking is in fact one of the most important means of communication.
(4) 既可以是正常语序也可以是倒装语序, 例如:
例1：A new type of TV sets was among the products on display.
Among the products on display was a new type of TV sets.
(5) 既可以用简单句也可以用并列句或者主从复合句, 例如:
例1：Nowadays a lot of people work in office, spending most of their time indoors.
Nowadays a lot of people work in office and they spend most of their time indoors.
The committee refused to listen to our request.
如果被改成The committee turned a deaf ear to our request. 句子生动，增加了文采。