Kober反应用于定量测定的药物为（ ）
A．链霉素
B．雌激素
C．维生素Ｂ１
D．皮质激素
参考答案：B
改错。下列各句均有一处错，请找出并改正。
( ) 1. My family like to have fun together.
A B C D
( ) 2. West points right on a map.
( ) 3. Australia have beautiful beaches.
( ) 4. My grandmother is older than me.
( ) 5. Her grandfather is a old man.
气体经历如图所示的循环过程.在一次循环中，气体对外所作的净功是______.
