讲解first和at first的区别.（ ）he was afraid to take the airplane.A.First B.At first C.Firstly D.First time

讲解first和at first的区别.（ ）he was afraid to take the airplane.A.First B.At first C.Firstly D.First time
讲解first和at first的区别.
（ ）he was afraid to take the airplane.
A.First B.At first C.Firstly D.First time

讲解first和at first的区别.（ ）he was afraid to take the airplane.A.First B.At first C.Firstly D.First time
这里选B
at first是副词词组,意思是 起初、一开始.
first是形容词,第一个的,第一的.
单从意思来看,可以判断是B不是A,从语法来看,句子缺少副词做状语,也可以判断是B不是A.