She is a good girl ,as we all know.
她是一个好女孩,这一点我们都知道.
As we all know,he studies very hard.
正如我们大家所知,他学习很努力.
Politicians do it,too,as we all know.
政治家也做这个,我们都知道.
As we all know,smoking is very harmful.
大家都知道,吸烟非常有害.
要加,放前放后都加.
As we all know'Practice makes perfect.'
但是这个其实是并不用加的.
因为上面都是作为短语出现的.
加了也并不错.
I‘m sure that .后面是一定没有逗号的.
in other words 和in another word 一般都加,因为它们都是作为插入语出现的,为了区分于句子结构,通常要加.