He made up his mind to devote his life________ pollution ________happily.
A:to prevent; from living
B:to prevent; to live
C:to preventing; from living
D:to preventing; to live
夏天,剥开包装纸的冰棍会冒“白气”是____现象(汽化/液化);根据你的观察,在室内无风时,冰棍冒出的“白气”符合实际的是图____(甲/乙)。
(I)求证:MN∥平面ABCD;
(II)求二面角D1﹣AC﹣B1的正弦值.
Your mother always in you, right?