-- Whose book is this? It must .A. be CarlaB. belong to Carla’ sC. belong to CarlaD. i

问题补充：

-- Whose book is this?

-- It must .

A. be Carla

B. belong to Carla’ s

C. belong to Carla

D. is Carla’ s

答案：

A. be Carla

B. belong to Carla’ s

(答案→)C. belong to Carla

D. is Carla’ s

解析：句意：这是谁的书？肯定是Carla的。Belong to sb.属于某人，也可用名词所有格的形式改成be sb.’s. 句中有情态动词must，所以动词用原形，故选C。