The phrase "are exceptionally difficult and" is correct and usable in written English.
It can be used when describing something that poses a significant challenge or is hard to accomplish, often followed by additional information.
Example: "The tasks assigned to the team are exceptionally difficult and require a high level of expertise to complete successfully."
Alternatives: "are extremely challenging and" or "are particularly tough and".
Fatigue life prediction of rollingstock components is exceptionally difficult and computationally intensive as calculations need to be made at each stage of the life of a component/structure.
"The three trials, of which this was the second, were exceptionally difficult and sensitive".
Mining of Yogo sapphires was exceptionally difficult and remains sporadic today.
This type of trading is exceptionally difficult, and taking on day trading as a profession requires extreme discipline, patience, and time, as well as a passion for the markets.
This fundamental theme of natural ants has been used as a motivation to create counterfeit artificial ants that tackle the real-life optimization issues, which are exceptionally difficult to comprehend and are made in a similar way.
Synthesis of ethyl tert-buty ether (ETBE), a high-performance fuel additive, through reactive distillation (RD) is an attractive route, while its operation and control are exceptionally difficult due to its functional combination and complex dynamics.
Early researchers thought that fluoroquinolone resistance was unlikely to evolve, largely because resistant Escherichia coli mutants are exceptionally difficult to select in vitro (2 ) and because plasmid-mediated quinolone resistance remained unknown even after 30 years of nalidixic acid usage.
The State of the World's Children 2006: Excluded and Invisible is a sweeping assessment of the world's most vulnerable children, whose rights to a safe and healthy childhood are exceptionally difficult to protect.
'The State of the World's Children 2006: Excluded and Invisible' (www.unicef.org/sowc06) is a sweeping assessment of the world's most vulnerable children, whose rights to a safe and healthy childhood are exceptionally difficult to protect.
The commissioner says historic sexual abuse cases are exceptionally difficult: "Victims of abuse are often damaged by their experience and rarely disclose everything until they begin to trust officers".
