28. 如圖(一)所示的桁架屬於哪一類型?(A)芬克式桁架 (Fink Truss)(B)鋸齒狀桁架 (Saw-tooth Truss)(C)曲弦式桁架 (Bowstring Truss)(D)華倫式桁架 (Warren Truss)