1.  He may know that Gussie was waiting for him and he was not about departing the earth.

2.  I don't know it is a romantic dream of the ancient philosophy or the finish line of society progress, but I hope one day liberty, equality, and fraternity can break boundaries.

3.  We don't know for sure whether the temperature has risen this year in the snow-covered regions that feed the upper Yangtze, but, given the dramatic rise in the global average in recent months, it probably has.

4.  We can know that Jobs is the one who changed the status of computer in society.

5.  You don't know the relationship of the things around you and what will happen next.

6.  We should know that the differences between beautiful and ugly are not so simple.

7.  We all have known that every coin has two sides.

8.  We must know that it is just a driving force.

9.  Adults should know that it has a lot of bad effects on teenagers.

10.  I've known that your research team is working at the Digital Michelangelo Project.