A:y=sinx
B:y=cosx
C:y=tanx
D:y=sin2x
自信对于任何一个人都是至关重要的。下列体现自信态度的是 ( )
若手指划破后感染发炎,血检时往往会发现血液中哪一种成分增多( )
—What do you think of the book, Nancy?
—I think it's both useful and _______.