21.  Miraculously, considering more than five centuries of constant use, it has survived intact.

22.  Since the Great Room is adjacent to the kitchen and since Mrs. Tindall keeps her grand piano and small pipe organ there, it is in constant use.

23.  Sometimes hinges work loose, from constant use of the door.

24.  That is because performers today are very likely wearing -- discreetly or otherwise -- a tiny microphone, a bit of technological wizardry now in constant use.

25.  The drugs are generally effective but can be harmful with constant use.

26.  The first stuff to go is usually the hard drive or the power supply, and constant use or indiscriminate jolts of juice exacerbate the problem.

27.  The map received constant use.

28.  The phone is in constant use.

29.  They are too fragile and too valuable for constant use.

30.  This is a cookbook whose pages are destined to become stuck together from constant use.