It is know to all that it takes years of ( )practice to gain the skill of( )expert.

an
Ca;an
D/Aa;the
B/

B.
years of practise(practise不可数）类似的years of hard work
expert原因开头加a.

成为一名专家所应具备的技巧能力是需要多年的实践才能获得的;;an It is known to all that it takes years of practice to gain the skill of an expert. 众所周知B/

你好！ B/;an，因为practice 不可数，前面不能用 a， an expert 是泛指概念。 It is known to all that it takes years of practice to gain the skill of an expert. 众所周知，要拥有一名专家级的技能是需要经过多年的实践的。 我的回答你还满意吗~~

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