21.   All that noise makes it hard to concentrate.

22.   Cultural barriers have made it hard for women to enter many professions.

23.   A high-pressure job that makes it hard for him to loosen up even on weekends.

24.   This refusal to consider the issue logically makes it hard for even trained scientists and other experts to see the matter clearly.

25.   This inevitably makes it hard for us to become accustomed to making the distinction explicitly.

26.   Cold air like rushing water battered at his face, beating in his cheeks and making it hard to breathe.

27.   Entrenched competitors can make it hard for a supplier to win new orders.

28.   Her own shadow stretching ahead, making it hard to see it clearly.

29.   This makes it hard to claim categorically that there are no characteristically black features which might identify speakers as ethnic Caribbeans.

30.   Furthermore, defences -- mechanical or chemical properties such as tannins, which make digestion hard, or toxins such as alkaloids -- are no deterrent to some animals.