The phrase "activity is going on" is correct and usable in written English.
It can be used to indicate that some form of action or event is currently taking place.
Example: "There is a lot of excitement in the air because the activity is going on at the community center today."
Alternatives: "activity is occurring" or "activity is taking place".
Currently in plasma physics, high research activity is going on as a dust (y) plasma.
But significant, coordinated aid activity is going on inside the city this winter.
Of course, this kind of activity is going on in all the battleground states.
"The amount of hydrogen would reveal how much hydrothermal activity is going on".
"I have often seen people peering into the windows, trying to discover what kind of activity is going on inside".
The small area of woodland surrounded by houses where all this activity is going on was formerly used for fly-tipping and not much else; it has been transformed by the efforts of the Wansdyke Play Association WPAA), working in partnership with Somer, a local housing association, and now it is the children's domain.
The potted plants still lined the windowsills, but no activity was going on in their shade.
Robert Hou, who owns College Point's two 7-Eleven stores, denied that loitering and illegal activity were going on outside his stores and said Mr. Cohen's bill was unfair.
Hayes later e-mailed three of the scientists, telling them, "I was insulted, felt railroaded and, in fact, felt that some dishonest and unethical activity was going on".
"Unless you had access to tens of thousands of criminal complaints a year, you would never know this type of activity was going on in the parks".
While all the aforementioned activity was going on, the game official also warned the Burroughs boys' soccer team, which had sat on the visitors' side, to walk over to the home side.
