2019屆高考英語語法定語從句要點(diǎn)專題精講
as we know眾所周知
as has been said above/before正如前文所述
as has been pointed out正如已經(jīng)指出的
as might be imagined可以想像得到
當(dāng)定語從句的關(guān)系代詞指的是先行詞本身時(shí)，只能用which。如：
these apple trees，which i planted three years ago，have not borne any fruit.
這些蘋果樹是我三年前種下的，沒結(jié)出任何果實(shí)。
the thames，which is now clean enough to swim in，was polluted for over a hundred years.
泰晤士河，現(xiàn)在已經(jīng)很干凈，可以在里面游泳，它曾被污染了一百多年。
帶介詞的典型的定語從句，必須用which，不能用as。如：
there is a great deal of oxygen around us，without which we could not live.我們周圍有許多氧氣，沒有它我們就無法生存。
the shed in our garden，in which we often played，has lasted for a long time.
我們經(jīng)常玩耍的花園里的那個(gè)棚子，已經(jīng)有很長時(shí)間了。
2)引導(dǎo)限制性定語從句時(shí)which與as的區(qū)別：
先行詞如為表示物的名詞或代詞，在從句中又作介詞的賓語時(shí)，只能用which。如：
this is the pan in which i boiled the milk. 這就是我煮牛奶的鍋。
前面有as時(shí),引導(dǎo)定語從句的關(guān)系代詞用as，不用which。如：
there are as many dictionaries as are needed.所需要的字典都有了。
前面有such時(shí)，引導(dǎo)定語從句的關(guān)系代詞用as,不用which。如：
such women as know tom thought he was charming.
認(rèn)識湯姆的女人都認(rèn)為他很迷人。
i have never heard such stories as he tells.他講的那些故事我從沒聽過。
he is not such a man as i expected.他不是我期望的那種人。
前面有the same時(shí)，引導(dǎo)定語從句的關(guān)系代詞用as而不用which。如：
we are facing the same problems as we did years ago.
我們正面臨著和多年以前同樣的困難。
this is the same wallet as i lost.這只錢包與我丟失的那只相同。
i have the same trouble as you have.我和你有著同樣的困難。
總之，which與as引導(dǎo)定語從句的區(qū)別要在實(shí)踐中多體會，體會多了，才能正確運(yùn)用。五、定語從句中的謂語動詞與先行詞保持一致的問題
1.one of+復(fù)數(shù)名詞+關(guān)系代詞+復(fù)數(shù)形動詞。如：
titanic is one of the most wonderful movies that have been produced in hollywood.《泰坦尼克號》是在好萊塢拍的最好的電影之一。
2.the (only)one of+復(fù)數(shù)名詞+關(guān)系代詞+單數(shù)形動詞。如：
the great wall is the (only)one of the buildings on the earth that is seen from the moon.
長城是地球上惟一一個(gè)從月球上能夠看到的建筑。
3.當(dāng)關(guān)系代詞as或which引導(dǎo)非限制性定語從句，修飾主句內(nèi)容時(shí)，若as或which作主語，則從句的謂語動詞用單數(shù)形式。如：
great changes have taken place in china，as is known to all.
中國發(fā)生了巨大的變化，眾所周知。
4.其他情況
i，who am your teacher，will try my best to help you.我，你的老師，要盡全力幫助你。
to own a colour tv set in each family，which we thought was impossible twenty years ago，now becomes true.