do u know what i'm talking about~plz point out the worse

I'd correct this as: (Check with your teacher/tutor)

1) Higher potential disease exposure through human mobility
-- Human increasingly high mobility [were so fast -- is cantonese translated to english, not english]
-- Transportation systems are compact, efficient and relatively cheaper than ever before. They place relatively large number of people into a compact (small) space, increasing exposure to disease due to perhaps limited fresh air circulation, especially in trains.

-- Therefore, human diseases ARE more easily spread around the world (you are giving the statement/thought NOW, so it's present tense)
-- E.g. SARS quickly spread across globally in 2003, a lot of people, including different countries, died.
-- America, Canada, Taiwan, Hong Kong, China

(Overall, this is a good idea, just minor mixing up of ideas. Please do not copy word for word here - ask your teacher/tutor and see what they say.)

Yes, i can understand what you're trying to say. Yet, i think you can group the points together, to make it more clear and unabridged.

For example:

- People's mobility has greaty increased as the transportation network is huge and it's convenient for us to travel to other countries. Therefore, it's easier for disease to spread cross-border.

- E.g. many countries got involve in the epidemic of hepatitis when sars bursted out in 2003, a lot of people from different countries died.

But i don't understand about the point: America, Canada, Taiwan, Hong Kong, China