Studies of the human “sleep-wake cycle” have practical relevance for matters ranging from duty assignments in nuclear submarines and air-traffic control towers to the staff of shifts in 24-hour factories.
(A) to the staff of
(B) to those who staff
(C) to the staffing of
(D) and staffing
(E) and the staff of
why A is wrong? why C is correct?
thanks
(A) to the staff of
(B) to those who staff
(C) to the staffing of
(D) and staffing
(E) and the staff of
why A is wrong? why C is correct?
thanks
