Joining the English club at school was _____ best way to improve English.[ ]

A. the

B. /

C. a

D. an

促胰液素和促甲状腺激素的靶细胞分别是（）

A.小肠黏膜细胞和甲状腺细胞

B.胰腺细胞和甲状腺细胞

C.肝细胞和下丘脑细胞

D.胰岛细胞和垂体细胞