第21题: [单项选择]She is subject to frequent ______ from high spirits to depression. A. transformation B. transmission C. transference D. transition 参考答案:D 答案解析:transition“过渡时期,转变,变迁”,常可与from…to…结构连用,如a transition from cold to warm weather.由冷到暖的天气转变。本句意为“她的情绪常常