按密封原理(即密封垫片受力情况)垫片密封可分为哪几类?
参考答案:
强制型密封、自紧式密封和半自紧式密封。
Choose the right structure of the computer which is general used,such as PC8086,Z-80, IBM360/370.
A.Single Instruction Single Data
B.Single Instruction Multiple Data
C.Multiple Instruction Single Data
D.Multiple Instruction Multiple Data
用酒精的质量分数为60%的酒精溶液A和酒精的质量分数为25%的酒精溶液B配制酒精的质量分数为45%的酒精溶液C,则需要A.B两种溶液的质量比为[ ]
A.3:4
B.1:2
C.4:3
D.2:1