皮皮学，免费搜题
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【简答题】
()The tail assembly or empennage consists of two sets of surfaces, usually one horizontal and one vertical. The vertical element has a fixed part called the vertical stabilizer and a movable part called the rudder. The rudder is controlled by the pedals on the cockpit floor.
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皮皮学刷刷变学霸
举一反三
【单选题】呈圆柱形,质硬而韧,不易折断,断面纤维性强,并显粉性,皮部黄白色,木部淡黄白色,有放射状纹理及裂隙,具豆腥气的药材是
A.
黄芪
B.
甘草
C.
丹参
D.
党参
E.
桔梗