![light flight](https://s3.amazonaws.com/smrtenglish.com/core/ENGL120AVIA/unit08/8-1g1.jpg)
A: There aren't any direction finding units (DF) in this region anymore.
B: Where have they all gone?
Present Perfect Simple
The Past & Present
As we studied in Unit 7, English speakers use the Present Perfect to connect the past with the present. The Present Perfect always gives information about the present:
![maintenance guy](https://s3.amazonaws.com/smrtenglish.com/core/ENGL120AVIA/unit08/8-1g2.jpg)
We've run out of spare radios. Let's go to maintenance to get some more.
![crying](https://s3.amazonaws.com/smrtenglish.com/core/ENGL120AVIA/unit08/8-1g3.jpg)
You've embarrassed her. Now she's crying.
![office](https://s3.amazonaws.com/smrtenglish.com/core/ENGL120AVIA/unit08/8-1g4.jpg)
Steve isn't here. He's gone home for the day.
Passive
The passive form of the Present Perfect is have / has + been + past participle:
![open door](https://s3.amazonaws.com/smrtenglish.com/core/ENGL120AVIA/unit08/8-1g5.jpg)
The central computer room door has been closed. That's why it's a little warmer in here.
![data centre](https://s3.amazonaws.com/smrtenglish.com/core/ENGL120AVIA/unit08/8-1g6.jpg)
We need to call a DSC (data systems coordinator). One of the DME (distance measuring equipment) facilities has been broken into.
![sad guy](https://s3.amazonaws.com/smrtenglish.com/core/ENGL120AVIA/unit08/8-1g7.jpg)
Your ATC (air traffic control) application has been denied. I'm sorry.
New Information
Unlock full access by logging in. Registered users can explore the entire lesson and more.