【简答题】已知△ABC ∽ △A 1 B 1 C 1 ,AB:A 1 B 1 =2:3,则S △ABC 与S △A1B1C1 之比为______.
【简答题】已知△ABC ∽ △A 1 B 1 C 1 ,AB:A 1 B 1 =3:4,则S △ABC 与 S △ A 1 B 1 C 1 之比为______.
【单选题】All of the plants nowraised on farms have been developed from plants once grew wild.
【简答题】已知△ABC ∽ △A 1 B 1 C 1 ,AB:A 1 B 1 = 2 :3,则S △ABC 与 S △ A 1 B 1 C 1 之比为______.
【简答题】平面机构中,两构件通过 [填空(1)] 接触构成的运动副称为低副,通过 [填空(2)] 或 [填空(3)] 接触构成的运动副称为高副。A. 面B. 点C. 线
【单选题】通常应对不利的材料价格差异负责的部门是:
【单选题】( )是于云南亚热带的极高山地,从山脚河谷到峰顶具备了亚热带、温带到寒带完整的垂直带自然景观。
【单选题】All of the plants now raised on farms have been developed from the plants _____ in the wild.
【单选题】已知 C(s)+1/2O 2 (g) → CO(g) 的△ r H m =-110.5kJ·mol -1 , C(s)+O 2 (g) → CO 2 (g) 的△ r H m =-393.5kJ·mol -1 ,则 CO(s)+1/2O 2 (g) → CO 2 (g) 的△ r H m 为 ( )