The voyages of travellers before the 17^th century show that they were not ________ the sea even though they didn’t have modern navigational aids.

A．at the expense of

B．at the risk of

C．in the way of

D．at the mercy of

鉴定专家成员抽取为专家鉴定组成员，申请回避批准理由（）

A.为处理医疗事故争议提供医学证据

B.系当事人近亲属

C.涉及死因、伤残等级鉴定

D.与医疗事故争议无利害关系

E.与医疗事故争议当事人没有其他关系