船舶固定CO2灭火系统的布置,要求对能往机舱的管径和喷嘴数量,应使该舱所需CO2的85%能在()min喷入所需舱室。
A.1
B.2
C.4
D.5
参考答案:B
Generally, a farmer has more difficulty than a college graduate. [ ]
A. to earning livings
B. to ern his living
C. earning livings
D. earning his living
为用户与数据库系统提供接口的语言是
A.高级语言
B.数据定义语言(DDL)
C.数据操纵语言(DML)
D.汇编语言