Tại sao con heo bị bệnh dịch tả

imagine a line passing through the center of earth that goes through both the north pole and the south pole. this imaginary line is called an axis. earth spins around its axis, just as a top spins around its spindle. this spinning movement is called earth's rotation. at the same time that the earth spins on its axis, it also orbits, or revolves around the sun. this movement is called revolution.

"it built up in the atmosphere"

i think thats it, idk, i tried looking for this exact q& a for grad. and idk if i got this question right or sorry if im wrong

look at this it will give you up to 17 answers