I today's newspaper, but I found nothing new.
A:looked up
B:looked through
C:looked like
D:looked after
下列能源中,不来源于太阳能的是( )
(Ⅰ)证明:BC⊥AB1;
(Ⅱ)若OC=OA,求二面角A1﹣AC﹣B的余弦值.
综合与实践:制作无盖盒子
任务一:如图1,有一块矩形纸板,长是宽的2倍,要将其四角各剪去一个正方形,折成高为4cm,容积为616cm3的无盖长方体盒子(纸板厚度忽略不计).
做化学实验时,不慎打翻酒精灯,导致酒精在桌上燃烧,你认为最切实可行的措施是( )