The importance of a cheap, easy-to-access, reliable and integrated public transport system is difficult to exaggerate.
When any single source of fuel accounts for even a third of the power flowing into a grid, the security of that system is difficult to guarantee.
The Commons first-past-the-post system is difficult to defend, as support in many seats is split between three or even four serious contender parties, and many votes are "wasted".
Our parties can't do that, partly because the big parties, particularly Labour, remain rooted in old tribal politics, and partly because our unfair electoral system is difficult to second-guess.
The career mode is extremely tough at first as you start off in a very low-powered car, plus the handling is extremely tough and the collision system is difficult to get used to.
The impact on the electric system is difficult to quantify, in part because the administration is moving forward on two other major rules affecting power plants, one for plants east of the Rockies that send pollution across state borders, and another governing discharges of warm water.
Trying to unpack the patent system is difficult.
Frequency forecast in a power system is difficult and challenging.
However, the robustness of such a system is difficult to achieve when various interferences occur simultaneously.
Thus, controller design for redundant robot system is difficult job for controller designer.
The model of the whole system is difficult to be completely established before the diagnosis analysis.
