I have two sisters. They are _______.
A:woman teacher
B:woman teachers
C:women teacher
D:women teachers
世界卫生组织驻华代表说:虽然世界各国的卫生体系都在变革,但是中国的医改步伐超过了任何一个国家。我国加快推进医疗制度改革,这体现了( )
F1和F2是共点力,根据平行四边形定则求合力F,作图正确的是( )