【单选题】听下面的录音[bi3],请选出来正确的答案。
【多选题】中国进入到新民主主义社会后存在的三种主要经济成分是
【单选题】圆柱齿轮啮合时,在剖视图中,当剖切平面通过两啮合齿轮轴线时,在啮合区内,将一个齿轮的轮齿和另一个齿轮的轮齿被遮挡的部分分别用()来绘制,被遮挡的部分也可经省略不画。
【单选题】听下面的录音[pie3],请选出来正确的答案。
【简答题】超文本传输协议HTTP的端口号是______,文件传输协议FTP的端口号是__________,远程登录协议TELNET的端口号是______,域名解析服务器DNS的端口号是__________,简单邮件传输协议SMTP的端口号是________,邮局协议版本POP3的端口号是__________,交互式邮件存取协议IMAP的端口号是__________,简单文件传输协议TFTP的端口号是____...
【单选题】Motor vessels usually have independent lube oil systems for main engine and reduction gears because ________.
A.
coolers are not needed for the gear system
B.
contaminants produced by the engine could harm the reduction gears
C.
non-additive oils are used in the main engine system
D.
different type centrifuges are required for the main engine and reduction gear lube systems
【单选题】Motor vessels usually have independent lube oil systems for main engine and reduction gears because____
A.
coolers are not needed for the gear system
B.
contaminants produced by the engine could harm the reduction gears
C.
non-additive oils axe used in the main engine system
D.
different type centrifuges are required for the main engine and reduction gear lube systems
【单选题】听下面的录音[piao3],请选出来正确的答案。