把一根木条钉牢在墙壁上需要____ 个钉子,其理论依据是:____
— Is your father free these days?
—No. He has mountains of work to do. He gets up early and comes back late every day.
关于x,y方程组x2+2y2=6mx+y=3有一组实数解,那么m的取值范围是( )
输血以输____为原则,遇到紧急情况需少量输血时,ABO血型系统中,____型血的人可以给任何血型的人提供血液.