主要用于治疗小儿麻痹症后遗症、肌肉萎缩的药物为（）.

A．氟他胺 

B．非那雄胺 

C．左炔诺孕酮 

D．丙酸睾酮 

E．达那唑

I think we ______ be able to have holidays on the moon in about twenty years' time.

[      ]

A. are going to

B. will

C. can

D. would