参考答案：A

解析：[分析] 动词辨析。 countenance支持，赞成：How could you countenance such behavior 你怎么能纵容这种行为 support支撑，支持，拥护：These posts support the roof．这些柱子支撑着房顶。obscure使暗，使不明显：Smog obscured our view．烟雾模糊了我们的视野。conceal隐藏，隐蔽，隐瞒：He concealed the sweets in his pocket．他把糖果藏在口袋里。assist援助，帮助：We all assisted in mending the roof．我们都帮助修理屋顶。