作者：賈利民
1. [問(wèn)]Well, I saw many old inventions on show.句中on show 的前面可以加were嗎？
[答]可以。該句加were與否從意義上講相同，但從結(jié)構(gòu)上講有區(qū)別：原句屬于簡(jiǎn)單句，是"主+謂+賓"結(jié)構(gòu)，介詞短語(yǔ)on show作名詞inventions的后置定語(yǔ)；而I saw many old inventions were on show. 則是省略 that 的賓語(yǔ)從句。
2. [問(wèn)]They were all invented hundreds of years ago.英語(yǔ)中hundred 總是用復(fù)數(shù)形式嗎？
[答]不是。當(dāng)hundred, thousand, million 等前面有具體數(shù)字或several，且后接名詞時(shí)，既不能在詞尾加s，也不能在后面跟of；如果表示一個(gè)不具體的數(shù)量或是運(yùn)用夸張手法時(shí)，常用hundreds / thousands / millions of +名詞復(fù)數(shù)形式，分別表示"數(shù)以百計(jì)的"、"成千上萬(wàn)的"、"數(shù)以百萬(wàn)計(jì)的"。如：
There are about three thousand students in our school.
Thousands of trees should be planted on the mountains.
3. [問(wèn)]These must be dinosaur eggs. 這句話的否定句應(yīng)為：These mustn't be dinosaur eggs. 對(duì)嗎？
[答]不對(duì)。此句中的must 意為"一定是；肯定是"，表示肯定的推測(cè)，這時(shí)它的否定式為can't，意為"不可能；一定不"。mustn't 意為"千萬(wàn)不要；絕不能（做某事）"。因此該句改為否定句應(yīng)為：These can't be dinosaur eggs.
4. [問(wèn)]The ground must be just right -- neither too wet nor too dry.句中neither... nor... 應(yīng)如何理解和使用？
[答]neither... nor... 意為"既不......也不......"，是對(duì)所連接的并列成份的全部否定，其反義詞組為both... and...。在使用時(shí)，我們應(yīng)注意：（1）它所連接的作主、謂、賓、表、狀等成份的兩個(gè)結(jié)構(gòu)必須平行；（2）連接兩個(gè)平行的主語(yǔ)時(shí)，句中的謂語(yǔ)動(dòng)詞必須與離它最近的那個(gè)詞保持人稱(chēng)和數(shù)的一致。如：
I neither smoke nor drink.
Neither you nor I am a teacher.
5. [問(wèn)]Dig a hole large enough for the tree. 句中的enough 可以放在large 之前嗎？
[答]不能。enough作副詞修飾形容詞、副詞時(shí)，只能置于被修飾詞之后。如：
Are you warm enough in such a light jacket?
6. [問(wèn)]The trees in the forests can keep rain drops from hitting the soil directly.與The Great Green Wall will stop the wind from blowing the earth away.這兩句話中的keep... from doing 與stop... from doing 意思和用法一樣嗎？
[答]一樣。keep/stop/prevent sb./sth. from doing 意為"阻止某人/某物做某事"。由于stop 和prevent 本身有"阻止"之意，因此， 二者該結(jié)構(gòu)中的from可以省略；keep沒(méi)有"阻止"之意，所以無(wú)論哪種結(jié)構(gòu)形式，from都必須保留。
7. [問(wèn)]In a few years' time those mountains will be covered with trees, too. 句中為何用in而不用after？
[答]in 與 after 都可表示"在......之后"，但它們不可通用。"in +一段時(shí)間"表示"在......之后"，常用于將來(lái)時(shí)；"after +一段時(shí)間"相當(dāng)于"一段時(shí)間+later"表示"在......以后"，常用于過(guò)去時(shí)；"after+時(shí)間點(diǎn)"表示"在某個(gè)具體的時(shí)刻之后"，可用于將來(lái)時(shí)或過(guò)去時(shí)。