Working all day long without any rest ____ ____ his ____.
He has two sisters. One is a doctor and is a teacher.
①星星之火,可以燎原 ②打倒列强,除军阀 ③誓死力争,还我青岛
关于平流层的叙述,正确的是( )
根据下列装置,结合所学化学知识回答下列问题.