The phrase "activity was not only" is correct and usable in written English.
It can be used when you want to emphasize that an activity has multiple aspects or benefits, often followed by "but also" to introduce another point.
Example: "The activity was not only enjoyable but also educational, providing participants with valuable skills."
Alternatives: "the activity was both" or "the activity was not just".
■ For elderly people, a group long considered sexually demure if not altogether chaste, vigorous sexual activity was not only possible but normal.
Locomotor activity was not only increased during the procedure, but also did not exceed the peak levels found during undisturbed wakefulness.
This reduction in activity was not only rescued when the YJU3 gene was reintroduced, but PEA hydrolysis was actually greatly increased (Figure 5A).
Finally, by using heterologous expression of LLO and purified LLO encapsulated in liposomes, we showed that LLO activity was not only necessary but sufficient to trigger autophagy.
This underlined that the predictive potential of catalase activity was not only restricted to mild stress conditions that induced enhanced robustness, but that it could also predict the lack of enhanced robustness following mild stress pretreatment.
We further showed that TF-fVIIa activity was not only localised on the cancer cell surface, but was also secreted into culture media as a component of MPs.
But studies have repeatedly shown that people who combine a moderate cutback in calories with regular physical activity are not only more successful in achieving their weight goals, but they are are also far more likely to keep off most, if not all, of the unwanted pounds.
Together, this exemplifies how histone demethylase activity is not only defined by the active site itself, but also requires complex interactions between the substrate and addition domains.
Another issue is that RIPK1 kinase activity is not only confined to necroptosis but is also involved in ERK activation and in apoptosis when IAP is depleted.
Human activity is not only draining the river and its aquifers of water, it is spitting gobs of poison into the flow that remains.
This type of activity is not only safe, but fun and beneficial – as after eight weeks speaking only French/German/Spanish, you're almost guaranteed an A in speaking tests and you'll probably go up a grade or two overall".
