不参与咽淋巴环构成的是（）

A.腺样体

B.咽侧索

C.腭垂（悬雍垂）

D.咽后壁淋巴滤泡

E.舌扁桃体

On a vessel，if someone fell overboard and you did not know over which side the person fell，you should（）.

A.immediately reverse the engines

B.stop the propellers from turning and throw a ring buoy over the side

C.increase speed to full to get the vessel away from the person

D.first put the rudder hard over in either direction