三糖铁琼脂培养基三糖铁主要指哪三种糖？
参考答案：葡萄糖、乳糖、蔗糖。
Mr. Blake ____ Shanghai in a few days. Do you know when the earliest plane ____ on Sunday?
A．is leaving, takes off
B．leaves, takes off
C．is leaving, is taking off
D．leaves, is taking off
下面刀具材料中，综合性能好、应用范围较广的一种材料是（）。
A.碳素工具钢
B.陶瓷
C.高速工具钢
D.低碳钢
