11.   The difficulties are most acute for those associations specialising in short-term accommodation and for those finding housing for refugees and asylum seekers.

12.   The difficulties were considerable for aircraft were still primitive with open cockpits, and airfields were very few and far between.

13.   The difficulty is greater in relation to overseas Markets having temperatures and humidities higher than those of temperate regions.

14.   The difficulty is that of translating the verbal problem or formula into the correct operations in the correct sequence.

15.   The difficulty is that, however strong in outline, the characterization turns out to be weak in detail.

16.   The difficulty is to find a good description language in which to express the learning situation.

17.   The difficulty was always to obtain sufficiently high-quality data within a defined area.

18.   The difficulty with habits is that they are difficult to change.

19.   The main difficulty is that such heavy feeders are easy to overfeed and are capable of quickly fouling the aquarium water.