A:b<a<c
B:c<a<b
C:c<b<a
D:a<c<b
已知函数fx=cosx+sinx,则f'π4=____ .
A. No, it isn't.
B. It's a bear.
C. Tigers eat meat.
D. It's on the chair.
E. In a tree.
制作人体口腔上皮细胞临时装片时,漱口的液体、载玻片上滴加的液体、染色用的液体分别是( )