---At present one of the best ways to study is working in groups.-More chances to stu

问题补充：

---At present, one of the best ways to study is working in groups.

---More chances to students to learn from each other.

A. offer

B. are offered

C. have offered

D. are offering

答案：

A. offer

(答案→)B. are offered

C. have offered

D. are offering

解析：句意：目前，最好的学习方式之一就是小组学习。提供给学生彼此学习的更多的机会。动作的承受者作主语，用被动语态。其结构是，主语+be+done.根据句意，故选B