"forms a challenge" is a perfectly correct and usable phrase in written English.
You can use it to describe a difficult situation that someone is facing. For example, "She was faced with the daunting task of studying for multiple exams, which formed a challenge for her."
Lawyers who have examined the topic say there is not just confusion about the provision itself, but uncertainty about who would have the legal standing to challenge a candidate on such grounds, what form a challenge could take and whether it would have to wait until after the election or could be made at any time.
Further, the atria are anatomically complex, comprising many regions of different geometrical structures [ 16], which form a challenge for an accurate reconstruction of these regions and numerical treatment of the nodes by FEM.
Data capture with CJRR forms remains a challenge: only 41% of all TKAs and THAs had forms submitted to the CIHI in 2006 7.
Also the low abundance of individual forms is a challenge in the study of extrahepatic CYP-related toxicity.
Violence against children in all its forms remains a challenge for societies in the world," said Ms. Coomaraswamy.
The genetic diversity of HIV-1, comprised of multiple subtypes and intersubtype recombinant forms, poses a challenge to the evaluation of drug resistance.
Violence against children in all its forms remains a challenge for societies in the world," said Radhika Coomaraswamy," the Special Representative of the Secretary-General for Children and Armed Conflict.
The analysis of proteins in biological membranes forms a major challenge in proteomics.
Since the main source of Internet traffic is small file web transfers, this issue forms a major challenge in current WLANs which is called size-based unfairness.
