下列四条线段成比例的是( )
A.1cm,2cm,4cm,6cm
B.3cm,4cm,7cm,8cm
C.2cm,4cm,8cm,16cm
D.1cm,3cm,5cm,7cm
答案:C
符合甲状腺功能亢进症代谢率增高的表现是()
A.神经过敏、失眠
B.心动过速、收缩压增高
C.肠蠕动增快、腹泻
D.甲状腺弥漫性肿大
E.怕热、多汗、食欲亢进
Firms in a perfectly competitive industry will increase their output until which of the following conditions is met()
A. Total revenue equals price.
B. Marginal cost equals price.
C. Marginal revenue equals average fixed cost.