"grave obstacles" is correct and usable in written English.
You can use it to describe difficult situations which require exceptional effort or courage in order to be overcome. For example, "The expedition faced grave obstacles in their attempt to scale the mountain."
On Sunday, it said the Security Council's action "has thrown a grave obstacle" in the way of its efforts to focus on "economic construction so that the people may not tighten their belts any longer".
The EU's emissions reduction target for 2020 could be facing an unlikely but grave obstacle, according to a growing number of scientists, EU officials and NGOs: the contribution of biomass to the EU's renewable energy objectives for 2020.
The occurrence of inequivalent representations is a grave obstacle for interpreting QFT, which is increasingly rated as the single most important problem, that has no counterpart whatsoever in standard QM.
The violence that is lived and learned in the home and the violence that exists in society are intertwined; the transmission of intergenerational violence, which is a grave obstacle to achieve the Millennium Development Goals to create more just and stable societies, has to be stopped," affirms Nils Kastberg, UNICEF's Regional Director for Latin America and the Caribbean.
There are serious obstacles.
Even as the tone may was more grave than ever, the ultimate obstacle for the international coalition will be to reach and enforce a collective agreement.
Even as the tone was more grave than ever, the ultimate obstacle for the international coalition will be to reach and enforce a collective agreement.
The many similarities in these perspectives indicate a grave concern on crucial security and legal obstacles for cloud computing, including service availability, data confidentiality, provider lock-in and reputation fate sharing [7].
When James Hodgkinson opened fire upon a field of Republican congressmen, he acted with a grave worldview as his inspiration; according to which, all obstacles were to be vanquished from the earth.
John McCain returned from the grave to capture the nomination from better-funded rivals.The complicated obstacle course is about as good a test of a potential president's character as you can devise.
