A:that; whe
B:when; that
C:that; where
D:where; that
We our teacher our party yesterday.
已知,如图,下列条件中不能判断直线l1∥l2的是( )
潜水、登山和宇航都需要用到氧气是因为它能____ ;气焊、炼钢需要用到氧气是因为它能____ .氮气的化学性质____ ,可用作____ ,氮气约占空气体积的 ____ %.