9.Still the classification into “learned” and “popular” is convenient and sound .

本句中的sound是形容词，意思是“正确的;明智的”，如：

He felt so happy that he had made a sound decision.

(做了正确的决定，他感到很高兴。)

请看下面几个句子，注意sound 在句中的意思：

1)He is sound in body and mind (他身心健康)

2)The house is sound .Don't hesitate to buy it (这所房了完好无损，别犹豫，买下它)

3)The baby is having a sound sleep.(宝宝在酣睡)

4)Father gave him a sound beating.(父亲给他一顿痛打)

10.When we call a word “learned” we don't mean that it is used by learned persons alone， but simply that its presence in the English vocabulary is due to books and the cultivation of literature rather than to the actual needs of ordinary people

not (that)…but (that)。意思“不是…。而是。”如：

1)I came here again not because I enjoy the scenery so much but because I like the people .

(我又来这儿，不是因为我多喜欢这儿的景色，而是我爱这儿的人们。)

2)By calling him Shylock， I don't mean that he is named Shylock，but that he is as miserly as Shylock.

(叫他夏洛克，我不是说他的名字叫夏洛克，而是说他像夏洛克一样吝啬。)

due to 在句中的意思是“由于”，如：

1)His failure was due to carelessness (他的失败是由于粗心。)

2)Due to lack of funds，they had to postpone the project.(由于缺少资金，他们不得不推迟计划)

rather than 在本句的意思是“不是…而是……”，“与其……不如…”

1) He is a writer than a teacher (与其说他是教师，不如说他是作家。)

2)He lay rather than sit in the armchair (与其说他是坐在扶手椅上不如说是躺在里面。)