题目:
Since the 1930s aircraft manufacturers have tried to build airplanes with frictionless wings, shaped so smoothly and perfectly that the air passing over them would not become turbulent.
选项:
A、wings, shaped so smoothly and perfectly
B、wings, wings so smooth and so perfectly shaped
C、wings that are shaped so smooth and perfect
D、wings, shaped in such a smooth and perfect manner
E、wings, wings having been shaped smoothly and perfectly so
答案:
B