____ several times, but unfortunately, the boy still couldn’t smooth away the problem on his own.[ ]

A. Having been explained              

B. The problem having been explained

C. The problem had been explained

D. Although the problem had been explained

参苓白术散的功效为（）

A.抑肝扶脾

B.温肾健脾

C.消食导滞

D.清热利湿

E.健脾益胃