题干
—I want to make a kite to fly.
—________You can easily buy one at the market.
A：Why not?
B：Good idea.
C：Why bother?
D：No way!
答案(点此获取答案解析）
C
—I want to make a kite to fly.
—________You can easily buy one at the market.
A：Why not?
B：Good idea.
C：Why bother?
D：No way!
为△ABC的内角，则下列函数中一定取正值的是（ ）