41.   The play is well known to scholars and its authorship is still very much in doubt.

42.   The problem was making her presence known to any search party.

43.   The six people at a corner table were well known to the proprietor, who saw them regularly in the winter months.

44.   The students and her needs must be known to the ward staff if learning is to be effective.

45.   The stuff that furs up coronary arteries must be one of the most lethal substances known to man.

46.   The truth was known to no one other than herself.

47.   These are matters well known to everybody, with the details easily available in any basic biology book.

48.   This is one of the worst diseases known to man.

49.   This is secret information, known only to the Defence Department.

50.   This passage was already well known to Ash scholars and had been extensively quoted.