用方框中所给单词的适当形式填空。

         As we know, there are many beautiful places in China, such as Hong Kong, Harbin. They attract a lot of people at home and abroad. But it's hard for ____ to choose where they can go. You can tell them ____ Guide to China, which ____ China in detail. If they have no chance to go through the book, you may show them advertisements for traveling, then after ____, they can decide where to go. They will have a good trip and take photos in ____ of it.

在我国古代，人们常以“牛”、“耕”作为名、字，如孔子的弟子司马耕，字子牛；晋国有位大力士姓牛字子耕，这反映了牛耕技术在当时备受人们推崇。牛耕的使用开始于（    ）

在中央电视台“挑战主持人”的节目中，两位挑战者正在就“如何评价唐太宗李世民”展开对擂。请根据所学知识，回答问题。

马克思说，物质是人类的第一需要，没有物质，人类将不能生存．这里的物质应当指（  ）