Whatistheadvantageofexternalgearpumps?
A. highpressureofoutput
B. smoothandquiet
C. lowcostofproduction
D. Noneoftheabove
查看答案
Gearpumpsarefixeddisplacementpumps.
A. 对
B. 错
Crescentgearpumpsarevariabledisplacementpumps.
A. 对
B. 错
Somegearpumpsarevariabledisplacementpumps.
A. 对
B. 错
Many people have hobbies. They make things or _____ things. Right now, someone is enjoying a hobby somewhere. People collect _____, rocks, records, pictures, or china. Some people like to make ______. They could make a table, a chair or a boat, or make a cake, an apple pie or some ice cream. People with hobbies are not _____. They are interested in their hobbies because they can _____ their leisure activities. Some work and some play will make people interested, too.