71.  It is known to all of us that scientific literacy rate is of great importance to a nation's development and progress.

72.  It's known to all that people need friends.

73.  What is known to us all is that Internet has become an important part of our life.

74.  The harm to our society caused by the Internet is known to us .

75.  It's known to all that quite a number of countries use tri-color national flags, such as France and Russia.

76.  Firstly, it is wildly known to us that knowledge can be acquired from many kinds of sources.

77.  It is universally known that friendship is one of the eternal themes in all cultures.

78.  It's known that the Internet is a highway of information.

79.  It's known to us that the Internet is the information highway.

80.  Koalas are known for their precious fur.