推法中作用缓和，可治疗腰脊酸痛、胸腹胀痛等症的推拿手法是（）

A.拇指平推法

B.掌平推法

C.拳平推法

D.一指禅推法

E.食指平推法

The center of flotation of a vessel is（）.

A.the center of volume of the immersed portion of the vessel

B.the center of gravity of the water plane

C.that point at which all the vertical downward forces of weight are considered to be concentrated

D.that point at which all the vertical upward forces of buoyancy are considered to be concentrated