Alice is one of the students who I am sure always best in most difficult situations.A. do

问题补充：

Alice is one of the students who I am sure always best in most difficult situations.

A. do her

B. do their

C. does her

D. does their

答案：

A. do her

(答案→)B. do their

C. does her

D. does their

解析：考查定语从句的主谓一致，定语从句的谓语和先行词一致，这题定语从句的I am sure是插入语，先行词是one of the students，说明努力的学生很多，爱丽丝是其中一个，谓语用复数，用their代替the students。选B。