"several problems exist" is a grammatically correct and usable phrase in written English.
It can be used to introduce a statement or discussion about multiple issues or difficulties that are present. Example: Several problems exist with our current marketing strategy. First, our target audience is not clearly defined. Additionally, our messaging is not resonating with potential customers. Finally, our budget allocation is not maximizing our return on investment.
However, several problems exist with these single component oxides due to their similar sensitivity to different gases.
However, several problems exist.
Several problems exist with the above described basic approaches, most notably: CL-rules are theoretically stable for x 0 = 0, but ISO learning is highly sensitive to numerical errors which can easily destroy convergence.
Several problems exist in the urban health system, for example, health resources were allocated to different levels of health facilities with little going to community health services, resulting in under development of these services in both preventive and curative health care.
Several EFTR procedures have been described, and several problems existed when EFTR was performed using an ESD device.
However, several problems exists, such as the high cost of the equipment; as with other new intraoperative techniques, there is a relevant learning curve; an additional incision has to be performed, in order to attach the reference clamp.
However, there are inconsistencies in the various recorded applications and several recurring problems exist.
Several methodological problems exist, for example relating to competing events, non-random censoring, non-proportional hazards and dependent observations.
Goal 7 – Ensure Environmental sustainability: Due to rapid urbanization, industrialization and heavy population density along the limited and confined green valley of the River Nile, several environmental problems exist.
Second, although the diagnosis of diabetes based on the HbA1c values has many advantages, several problems also exist.
Although there is compelling evidence that FSS is the primary morphogenic physical factor that determines the size of an artery and in particular the size of a growing collateral vessel, several problems still exist [ 85, 113, 114].
