We were all disappointed at _____.
句意：我们都对那个男孩所说的话感到失望。宾语从句要用陈述语序，先排除 A 和 C；再根据主句的时态 “一般过去时”可知答案为 D。
根据句意和汉语提示写出所缺的单词
国家公园对于保护野生动物免受屠杀是很重要的。
Theparks are very important to protect the wild animals from being killed.
根据汉语意思完成句子，每空一词
为了避免浪费资源，我们必须尽可能多地循环利用。
In order toresources,we must recycle them as much as possible.
avoid “避免”，其后若跟动词，只能用动名词，avoid doing sth. 意为“避免做某事”。