[名词解释] 抚养比(dependency ratio)
[名词解释] DNB比 DNB ratio(DNBR)
[名词解释] P/O比(P/O ratio)
[名词解释] 儿童妇女比(child-women ratio)
[名词解释] 流产(abortion)
[名词解释] 稽留流产(missed abortion)
[名词解释] 难免流产(inevitable abortion)
[名词解释] 不全流产(incomplete abortion)
[名词解释] 完全流产(complete abortion)
[单选题]In the suction stroke air is induced into the cylinder ()In the compression stroke the air is compressed.A . by an fuel valveB . through an inlet valveC . with an exhaust valveD . from an outlet valve