11.   I could hear strange voices outside the room.?

12.   For this reason lupins, poppies, carrots and parsnips are notoriously difficult to transplant successfully.

13.   Fruits ripened on the vine are tasty but soft and difficult to transport.

14.   He would not share power because it is difficult to share.

15.   Hoped-for rents never materialized, and a complex financial situation became even more difficult to control.

16.   However, many knitters find that it is still difficult to plan and knit garments.

17.   However, the techniques are still difficult to use in practice for arbitrary initial data.

18.   Ingrained attitudes and habitual ways of thinking are very difficult to change.

19.   It can be very difficult to Decide how to measure performance at many jobs.