複選題
44、 The boundary layer flow over a flat plate with zero pressure gradients is shown in Figure 44. The control volume is defined as dashed line a-b-c-d and the depth is defined as w. Ahead of the plate the velocity is uniform, U. The velocity distribution across cd is approximated by  , here  denotes the boundary layer thickness. Which of the following statements is correct? 
(A) the mass flux across bc equals ,
(B) the mass flux across ab equals  ,
(C) the mass flux across cd equals ,
(D) the mass flux across bc equals