1. register and style
formal versus informal

2. anglo-saxon vs romance
The first thing one notices in formal English is
that most words used are of Romance origin.
These can be recognized by:
French spelling
Latin origin
usually one-word verbs

3. the social dimension
A writer enters into a relationship with his
readers; an audience he is not familiar with. It
is the convention to take a formal stand
towards this audience, for reasons of respect,
certainly not for reasons of conceit.

4. taking distance
Formal writing demands impersonal
constructions in which we use:
Passive constructions that take away the agent;
Abstract nouns and nominalisations.

5. taking distance
Be reminded, though, that passive sentences
and a lot of nominalisations can make
sentences unclear to the reader. Sometimes an
active sentence can be better for the sake of
clarity.

6. example
I measured the temperature and checked if the
fluid was still transparent.
becomes:
The fluid was measured and checked for
transparency.

7. contractions
Contracted or abbreviated verbs pretend to imitate our
speaking habits. Therefore, writing skills do not allow
verb contractions but only fully-written verbs.
Compare:
He doesn't .... He does not....
I'd like...... I would like....
Please note:
He'd better research... He had better research...
It can't be concluded... It cannot be concluded...

8. contracted verbs
Avoiding to use fully-written verbs could give
the impression that the author is not serious
about his topic, creating thus a possible risk of
a breech of trustworthiness by the reader.