胆结石术后，取半坐卧位的目的是（）
A.减少手术后出血
B.利于腹腔引流
C.减轻伤口缝合张力
D.减轻疼痛
E.减轻腹胀
参考答案：B, C, D
基底部有纵纹，能主动吸收钠的唾液腺上皮细胞是（）
A.闰管细胞
B.肌上皮细胞
C.分泌管细胞
D.浆液性腺泡细胞
E.黏液性腺泡细胞
Why is it necessary to extend ventilators of gasoline powered vessels to the bilges（）.
A.To keep them dry，and thus easier to clean
B.To remove fuel vapors which are heavier than air
C.To provide adequate air to the engines
D.To cool the machinery areas
