---How did you work out the difficult chemistry problem?

--- I worked it out by ________.

A．working with a group

B．think very hard

C．ask the teacher for help

D．doing oneself

痉挛型脑瘫时髋的获得性半脱位或脱位通常是由于肌肉不平衡与牵拉，这些肌肉是()

A．髋屈肌与外侧筋膜阔张肌

B．髋屈肌与髋收肌

C．股直肌与髋展肌

D．外侧筋膜阔张肌与髋伸肌

E．髋展肌与髋伸肌