Present Perfect is commonly used in everyday speech – in professional context, it is particularly suitable for example for job application process to talk about one’s achievements and experience.
It refers to actions that were completed or started in the past, but we look at them from
the perspective of the present.
Present Perfect Simple is used when we focus on:
the result is important,
he amount (how much/how many) of something done.
I have managed to run several training programs all over the United Kingdom.
In my current position, I have developed and successfully implemented three complex software products.
Present Perfect Continuous is used when we focus on:
actions still in progress,
how long something has been going on.
I have been participating in this project for two years.
Peter has been writing his CV all afternoon.
Past Perfect is used to talk about actions that happened in the past and we look at them from
the perspective of another event in the past. In work environment it could be used to talk for example about past individual careers or a company’s past accomplishments, or simply sharing office stories.
Past Perfect Simple is used to talk about:
a completed action which happened before other past events,
an action completed before a specific time in the past.
After the important meeting Ms. Johns thanked Jennifer who had managed everything.
When Simon sent the mail, he realised that he had forgotten to attach the document.
Past Perfect Continuous is used to talk about:
to talk about a continuous action that was going on before other past events,
to say how long an action was going on before a specific time in the past.
I had been writing the report for three days when my boss told me it was not needed after all.
In 2006, I’d been already working in the company for five years.
These are structures to talk about situations when somebody causes another person or thing to do something. Simply speaking, things get (not) done, even though it is not you who (don’t) do them. It is quite useful when talking, for example, about delegating work within corporate hierarchy.
A causative structure can be active, i.e. we know who delegates to whom:
Mr. Headhunter had Jennifer write the candidates’ evaluations. (He told her to write it.)
I had our IT guy fix my crashed computer. (I called him to do it.)
Or it can be passive, when we do not know the doer, or they are unimportant, obvious etc.:
My boss had a new computer installed in his office. (Somebody competent installed it.)
Every other Monday, we have our company cars serviced and washed. (People in the garage do it.)
There are some other causative forms, let us mention the following:
Our boss is wonderful. He lets us take our dogs to the office. (He allows it.)
The management make us wear smart clothes at work all week. It’s rather uncomfortable.
(They force/compel us to do so, we’d rather wear something casual.)
As you can see from the examples, in the above mentioned causative structures the causative verb (have, make, let) is followed by infinitive without to.