But it wasn't clear whether this is due to reduced oxygen levels at high altitude or because their mothers are under-nourished — many people who live at high altitudes are relatively poor compared with those living lower down.
But it wasn't clear whether this is due to reduced oxygen levels at high altitude or because their mothers are under-nourished — many people who live at high altitudes are relatively poor compared with those living lower down.
但是还不清楚这是由于在高海拔的地方氧气不足，还是由于他们的母亲没有获得足够的营养——许多住在高海拔地方的人相对都比住在低处的人穷。