所以正確并熟練地使用以上聽力真題中的虛擬語氣的句型，尤其是其中的“if…would”這樣最基本的虛擬語氣句型，是拿到語法高分的一個(gè)很重要的因素。

【利用指數(shù)】★★★★★

高級語法使用(Higher Level Grammar)

七分必備語法之情態(tài)動(dòng)詞完成時(shí)：

【聽力真題】

The early farmers kept various animals, including cattle and sheep. There’s also evidence of pigs, but it is possible that these could have been descended from the native wild species….so we must assume that form the beginnings of Neolithic farming the number of breeding sheep would have considerably exceeded three hundred, and the national catle erd must have been of a similar size…but this method would have severely restricted the range of the colonising fleets. The sheer volume of animal transport necessary means it’s unlikely that this livestock could have been brought from anywhere further than England…the body of the plough would have been of wood and could have been drawn by people, but it’s also likely that cattle were used… however, after the axe had been chipped into shape, they needed water and sand for grinding and polishing, so a high mountainside wouldn’t have been an appropriate place for this. So this final stage of the manufacture must have been carried out close to water and sure enough, there’s ample evidence of this at coastal sites… after firing, the outside was often polished. This would have helped the pots of retain water, as they weren’t glazed… this could have been an limitation of earlier vessels which were made of leather sewn onto wood.

【相關(guān)點(diǎn)評】
　
以上我們選取了劍橋6 test3 section 4中的聽力原文進(jìn)行分析，因?yàn)閳鼍笆顷P(guān)于新石器時(shí)代的畜牧，農(nóng)耕和陶器制作等的講座，所以需要大量地表達(dá)對過去事實(shí)的推測，因此我們可以聽到頻繁地出現(xiàn)了情態(tài)動(dòng)詞+動(dòng)詞完成時(shí)的結(jié)構(gòu)：

Could+ have done：表示“過去本來可以做某事，但實(shí)際上沒有做”

Would+ have done：表示對過去事情的假設(shè)，意思是“本來會做”

Must+ have done：用于肯定句，表示“過去一定做過某事”，表示一種很有把握的推測。

除此之外，還有類似的結(jié)構(gòu)，如：

should (ought to) have done ：表示過去應(yīng)該做而(實(shí)際)沒有做的事情,含有責(zé)備或遺憾的語氣，意為“本應(yīng)該……”

needn’t have done：表示過去沒有必要做某事，但實(shí)際上做了某事

may/might have done：表示對過去情況的一種不太有把握的可能性推測，表示“過去可能/大概已做了某事”

在雅思口語真題中，有大量題目都是針對過去發(fā)生的事情，所以需要表達(dá)對過去的各種推測的語氣時(shí)，正需要這種結(jié)構(gòu)，例如：

【真題舉例】

Part 1：

When was the last time you gave flowers to someone?

What subjects are you studying?

Why did you choose to study that subject?

Part 2：

………………………………………………………………………………………………………………………………

Describe an antique or some other old thing that your family has kept for a long time.

You should say:

what it is

when your family first got this thing

how long your family has kept it

and explain why this thing is important to your family.