I have only been studying a short while in spare time but have seen quite a few simple sentences in which 而 precedes the verb. Are there any basic ideas about the structure of such sentences? Places where this is required, recommended? What really is the meaning of 而 in such a sentence? 

My notes aren't in front of me but I will supplement this later with an example if I can find one and the question is too broad. If it helps, I am only concerned with very simple sentences of this type. 

Edit: (I will replace the toneless Pinyin time allowing, meanwhile I am sure the translations will take care of any ambiguity.)

1. Ta ying wo de qing qiu er lai. (He came at my request.)
2. ...dui mian er zuo...(sitting opposite each other)
3. ...bu gao er qu...(leaving without announcing)
4. ...yi dai er guo... (mention in passing)
5. ...yan bi er guo ...(hold one's nose in passing, i.e. look down on)

I will look at the answers as soon as possible. My sense is that 'er' functions as a marker of the infinitive and maybe gives a sense of the manner in which the verb is being done or the reason for it. Thanks.