根据英文解释,给出对应的单词: 1. (of a book, film etc) very serious and may be difficult to understand-- ____________________ 2. in a sudden and surprising way or in a way that is easy to notice -- ______________________ 3. a quantity of sth. that is a part or share of the whole -- ____________________ 根据中文意思,填入对应的单词: 4. Opera has developed a reputation as a cultivated, __________________ sort of entertainment. 歌剧作为一种文雅且高雅的娱乐形式而声名远扬。 5. On average, fathers spoke less than mothers did, but they did not differ in the length of utterances or __________________ of questions asked. 平均来看,父亲说的话比母亲说的要少,但是从表达的长度或者提问的多少来看,父亲和母亲之间没有什么区别。 6. Infant mortality has been ______________________ reduced because of modern medicine. 现代医学使得婴儿死亡率极大地降低了。