________ he was a little shy in class, but now he acts more naturally.

________ he was a little shy in class, but now he acts more naturally.

A.First

B.At first

C.First of all

D.For the first time

答案及解析： B

解析：

【巧解导析】first，first of all表示一系列动作的开始，译为“第一”、“首先”，故不选A，C；

for the first time为“第一次”故不选D．