Mike is than his friend Sam.A. tall B. taller C. tallestD. the tallest

问题补充：

Mike is than his friend Sam.

A. tall

B. taller

C. tallest

D. the tallest

答案：

A. tall

(答案→)B. taller

C. tallest

D. the tallest

解析：根据句子的意思，可知两个人在进行比较，根据后文中有than，说明是用比较级，故选答案为B