—I'm making a model plane.
A:What is it?
B:What is he doing?
C:What are you doing?
下列关于实验室制取氯气的操作正确( )
①用药匙向烧瓶中加入浓盐酸,再向分液漏斗中装入MnO2粉末;②用酒精灯直接加热烧瓶;
③需检查装置的气密性;④多余氯气用NaOH溶液吸收;⑤可用装有碱石灰的干燥管干燥氯气.
①政治孤立
②经济封锁
③军事包围
④主动建交
帮三位小动物找位子
在各种海洋污染中,对海洋生物造成危害最大的是( )
When they faced such a difficulty, no better plan ____(出现,想出)to them.