The factory last month because it caused too much pollution.
A:closed down
B:fell down
C:hurried up
D:got up
-How do you come here? You look tired(累的). -________.
设m是平面α内的一条定直线,P是平面α外的一个定点,动直线n经过点P且与m成30°角,则直线n与平面α的交点Q的轨迹是( )