Sentence examples for often difficult to establish from inspiring English sources
It is not known whether the bird died because it ingested so much debris, and it is often difficult to establish whether plastics kill marine life.
However, it is often difficult to establish which elements are associated with organic matter versus the various mineral phases using whole rock data alone.
For the real time monitoring of deflections under operating traffic loads, it is often difficult to establish a fixed reference point for displacement transducers either because the bridge crosses over a body of water or a roadway.
Recently, surface topography has been shown to influence stem cell differentiation; however, general trends are often difficult to establish due to differences in length scales, surface chemistries and detailed surface topographies.
An independent assessment of the US-led air campaign by monitoring group Airwars has identified several reports of more than 750 non-combatants killed, although because of the multinational nature of the campaign it is often difficult to establish which nations carried out problematic strikes.
Although lines of demarcation are often difficult to establish, the most prominent of the numerous Dayak subgroups are the Kayan (in Kalimantan usually called Bahau) and Kenyah, primarily of southeastern Sarawak and eastern Kalimantan; the Ngaju of central and southern Kalimantan; the Bidayuh of southwestern Sarawak and western Kalimantan; and the Iban of Sarawak.
Copyright infringement is often difficult to prove in the video games industry, where competing publishers and developers often produce very similar titles in established genres.
end{cases} We note that it is not easy to use critical point theory to study FBVPs since it is often very difficult to establish suitable function spaces and variational functionals for FBVPs.
It is often very difficult to establish a suitable space and variational functional for fractional boundary value problem, especially for the fractional equations including both left and right fractional derivatives.
However, to the best of the authors' knowledge, there are few results on the solutions to fractional BVP which were established by the nonsmooth critical point theory, since it is often very difficult to establish a suitable space and variational functional for fractional differential equations with boundary conditions.
In the remainder of this paper, we illustrate the relation between the midlatitude positive bays and several other indicators of substorm onset and show why it is often so difficult to establish an accurate time sequence of events occurring during a substorm.
