-- Could you tell me __________ yesterday?
-- Because my bike was broken on my way here.
下列说法正确的是( )
已知α∈R,sinα+2cosα=102,则tan2α=( )
某化学兴趣小组准备对实验室一定量的粗盐进行提纯,并利用得到的精盐配制一定量一定浓度的食盐水,下列说法中正确的是( )