From an analysis of the data collected about the client who has had a gastric resection, the nurse formulates the nursing diagnosis Risk for ineffective airway clearance. Based on which of the following postoperative factors would the nurse make this diagnosis

A. Incisional pain.
B. Nausea.
C. Progressive ambulation.
D. Maintenance of a semi-Fowler’s position.

用如图所示滑轮组拉起G=100N的重物，不计轮与轴的摩擦和滑轮的重力，拉力F为

A．25N

B．12.5N

C．100N

D．200N