Explanation: Permission MUST be obtained when using...

Please explain the following sentence:

“Permission MUST be obtained when using outside sources”

Why can’nt we say:

“Permission MUST be obtained when we are using outside sources”

Please define the complete structure of the above sentence in details.


Hi Riaz

This is called ellipsis in English. When the meaning of some sentence is understood without a word or two in it, we leave those words out, and this is called ellipsis. See below for some examples of ellipsis.

1- What time did he die?
(Ans) He died at two in the morning.
(Ans) At two in the morning.(More natural than the first

2- When in Rome, do as Romans do. is better than:
When you are in Rome, do as…

In your spicific example, the “we are” is understood, so the author prefers to use ellipsis.

I hope this helps.


Thank you for your reply.

it is for the first time I am encountering the world
called ellipsis in English. I will appreciate if you could kindly provide me more details on the use of ellipsis…

thanks once again