Test!

This was developed as an age test by the R&D Department at HarvardUniversity . Take your time and see if you can read each line out loudwithout a mistake. The average person can't do it! This is really difficult, not so easy, so be careful.
1. this is this cat
2. this is cat
3. this cat knows that
4. This is how cat
5. This is to cat
6. This is keep cat
7. This is a cat
8. This is fool cat
9. This is busy cat
10. This is for cat
11. This is forty cat
12. This is seconds cat

Now go back and read the third word in each line from the top down,and I bet you can't resist passing it on.