40．Shown together with those products, some advanced ones made abroad included______, which greatly appealed to the visitors coming from all the corners of the world．

A．models of the new generation of airliners there were

B．there were models of the new generation of airliners

C．were models of the new generation of airliners

D．were there models of the new generation of airliners

螺旋桨排出流与吸入流比较，排出流的特点为：（）

A.流速较快，流线平行

B.流速较慢，流线平行

C.流速较快，流线旋转

D.流速较慢，流线旋转