拱式渡槽，根据主拱圈的结构形式（支撑结构特点），分为（）式渡槽、（）式渡槽和（）式渡槽。
参考答案：板拱；肋拱；双曲拱
China has special football schools where children acquire ball skills________a formal education.[ ]
A．as well as
B．as good as
C．as far as
D．as long as
易患皮下坏疽
A．佝偻病病儿B．链球菌感染C．由于新生儿皮肤娇嫩，白细胞趋化性差，免疫球蛋白不足D．肾上腺皮质激素抑制血细胞功能和抗体形成E．脊柱裂下肢瘫痪病
