The phrase "activity has often been" is correct and usable in written English.
It can be used when discussing the frequency or common occurrence of a particular activity in the past.
Example: "In recent studies, it has been shown that physical activity has often been linked to improved mental health outcomes."
Alternatives: "activity has frequently been" or "activity has regularly been".
Despite being a popular research topic in economics, sociology and urban studies, geographical clustering of human activity has often been studied by means of predetermined geographical units, such as administrative divisions and metropolitan areas.
While an imbalance in the electromyographic (EMG) activity has often been detected at the skin surface, very little information is available on the mechanisms by which such an imbalance could take place.
Velocity changes at Hakone volcano in central Japan, where remarkable swarm activity has often been observed, were investigated in this study.
In nature, food availability is hardly periodic to most rodents, and diurnal activity has often been observed in nocturnal animals [24] [26].
Prefrontal cortex [6] and anterior cingulate [37] activity has often been reported in categorization tasks, situations with errors [38] or response conflict [5], [39], [40], and during the early stages of motor learning [32], [41], [42].
The quality of the activity has often been described as disruptive and purposeless [ 6].
AMPs with high antimicrobial activity have been associated with high toxicity to transgenic plant cells, and peptides with moderate activity have often been expressed, including those especially modified to decrease the antimicrobial activity (e.g. MsrA1, [ 44]).
These activities have often been mocked — and were the source of scandal and outrage in the years before the revolution — but through Ms. Coppola's eyes they are poignant as well as a bit silly.
Although their beliefs and activities have often been opposed by Anglican Evangelicals, who stress the Protestant heritage of Anglicanism, Anglo-Catholics have continued to be an important force within the Anglican Communion.
Within the caldera, intense swarm activities have often been observed at depths of 0 km (sea level) to 8 km (e.g., Yukutake et al. 2010; Mannen 2003).
Structural/quantitative measures of social support, such as social network size and participation in group activities, have often been used to assess levels of social support (1, 2, 5, 6, 9, 17).
