---Shall I sit at this end of the boat or that end?-You may sit at end if you keep st

问题补充：

---Shall I sit at this end of the boat, or that end?

---You may sit at end if you keep still.

A. any

B. both

C. each

D. either

答案：

A. any

B. both

C. each

(答案→)D. either

解析：根据前面提问的this end or that end以及后面答语的句意可知答案。