"a usual situation" is correct and usable in written English.
You can use it whenever you want to refer to a typical or common occurrence. For example: "Driving in rush hour traffic is a usual situation on the roads of this city."
According to one public relations officer with the Council of International Students Australia, this isn't an usual situation for international students.
In either case, the existence of massive CNSs is not an usual situation compared with other invertebrate species closer to vertebrates.
It is a far from usual situation but, under Californian law, and over the protests of some legal rights campaigners, the evidence standards of conservatorship cases are much lower than those in criminal courts.
When the PI is the linear predictor from a model (the usual situation), the calibration slope is by construction exactly 1 in the derivation dataset.
It isn't the most usual situation for a founder to write a review trashing a competitor's new product, but Oculus co-founder Palmer Luckey has never been the most conventional entrepreneur.
Uniparental disomy represents a departure from the usual situation in which one member of each pair of chromosomes (called homologous chromosomes) is normally inherited from each parent.
In the first, people at high risk of contracting a life threatening cancer make life-style changes or receive continuous, chemopreventive therapies, and in the second, more usual situation, a tumour is discovered and removed, and the patient treated with specific cytotoxic or cytostatic chemicals and/or with radiation.
Indeed, in an inversion of the usual situation, it is out on Main Street -- Fulton, in this case -- that shoppers can find the Modell's, the Wiz, the Macy's.
