A:have stayed
B:have been staying
C:stay
D:will have stayed
如图为患血友病的某家族系谱图,该病为伴X隐性遗传,其中7号的致病基因来自( )
— Excuse me, sir. Please don't take photos in the museum. Look at the sign .
— I'm sorry. I didn't notice it just now.
小明用如图甲所示的电路,探究电源暗箱(图中虚线框所示)中电阻R0的阻值.