”Than that” ask again ??

我自己既理解黎睇...
因為第二句:
The climate of Japan is milder than that of the Canada
個that係指the climate...
即係其實句野都可以寫為the climate of Japan is milder than the climate of Canada. 只係因為咁寫會好累贅...所以用that..
加上佢有"of the"..."of the" 前面就要有個noun...所以用that...
但係第一句:
I can concentrate more studying in a Chinese restaurant than at home.
根本唔需要加that...
"I can concentrate more studying in a Chinese restaurant than that at home."
如果係咁既話...個that冇指明D咩架bor...
(以上係我既理解..)