参考答案：D

解析：结构识别。be engrossed in对……全神贯注的：I was so engrossed in his book that I forgot the time．我全神贯洼地看书忘记了时间。be involved in(与……)关系密切的，(与……)有牵连：be involved in politics热中于政治。delight in因……高兴，以……为乐：She delights in scandal．她对丑闻津津乐道。Frustrate使受挫折，令人沮丧：He was frustrated by his poverty．他因贫穷而灰心丧气。expand膨胀，扩大：expand one's knowledge of foreign countries扩大个人对外国的知识。