華閱文章網一、什么是半助動詞
半助動詞 在功能上介乎主動詞和助動詞之間的一類結構，稱為半助動詞。
常見的半助動詞有be about to, be due to, be going to, be likely to, be meant to, be obliged to, be supposed to, be willing to, have to, seem to, be unable to, be unwilling to等。它們可與主動詞搭配構成復雜動詞詞組并表示情態意義，有時也可與助動詞搭配。
例如： The boy has to make a living by begging. 男孩不得不通過乞討維持生計。 He is unwilling to help me with my English. 他不愿幫我學習英語。
Every clause is obliged to obtain a finite verb. 每個句子必須包括一個限定動詞。 We were about to start when it rained. 下雨時，我們即將出發。
He seems to be very disappointed. 他好像非常失望。 I don't have to buy a new house. 我不必買新房子。
He didn't seem to feel in love with her. 他好像沒有愛上她。 半助動詞的其他用法 帶有半助動詞作為動詞詞組的組成部分的句子，有的可以轉換為“ It…that-分句”結構，而有的卻不可以。
從這個角度看，半助動詞可分為兩類：一類是可以作上述轉換的，其中包括be cer-tain to,be(un)likely to,appear to,happen to,seem to等。例如： They are certain to win the game.他們肯定會在比賽中獲勝。
→It is certain that they will win the game. He is likely to let you down.他可能使你失望。 →It is likely that he will let you down. He appears to have many friends.看來他有許多朋友。
→It appears that he has many friends. He seems to be enjoying himself.看來他玩得很快活。 →It seems that he is enjoying himself. I happen to have had some nasty experiences in dealing with him. 我恰巧有過一些和他打交道的不愉快的經歷。
→It happens that I have had some nasty experiences in deal-ing with him. Some members of the committee seem to have been bribed. 委員會的一些成員看來是受了賄賂。 →It seems that some members of the committee have been bribed. 另一類半助動詞不可以作上述轉換，這一類包括be about to,be bound to,be going to,be to,had better,have to,have got to,tend to 等。
例如： He id adout to arrive.他即將到達。 He is bound to win.他一定會獲勝。
The boy tended to be late.這孩子老是遲到。 不可以轉換為： *It is about that he will arrive. *It bound that he will win. *It tended that the boy was late. 半助動詞也可用于there-存在句。
例如： There's going to be a storm.就要有暴風雨了。 There's to be an investigation.要作一次調查。
There has to be a mistake.一定有錯。 There's sure to be some rain tonight.今晚一定有雨。
There's likely to be a large audience.觀眾人數可能很多。 There's certain to be trouble at the factory.廠里一定有麻煩。
There seems to be a widespread change of attitude 看來態度有普遍的改變。 There appears to be no doubt about it. 看來這是毫無疑問的了。
凡是能夠作上述句型轉換的半助動詞，在there-存在句中，也可作類似的轉換。現在，我們再從相反的方向來看這種轉換關系： It is likely that there'll be a large audience. →There is likely to be a large audience. It is certain that there is trouble at the factory. →There is certain to be trouble at the factory. It seems that there's a widespread change of attitude. →There seeme to be a widespread change of attitude. It appears that there's no doubt about it. →There appers to be no doubt about it. 順便說一句，如果“It…that+there-存在句”的主句謂語動詞是is said,is believed等被動態，那末轉換過來的there-存在句的謂語動詞也應是被動態。
例如： It is said that there's trouble at the factory.據說廠里有麻煩。 →There's said to be trouble at the factory. 不過，這里的is said to(be)已經不是半助動詞了。
在結束本節以前，還要提一下半助動詞的省略式問題。在口語中，had better,have got to和be going to有時可用省略式。
例如： You('d) better go now.你最好現在就去。 You('ve)just got to *.你得幫幫我呀。
Where(are) you going to get the money from？ 你準備從哪兒去弄這筆錢？ be to結構在新聞標題中可以單用to-不定式表示： UNESCO CHIEF TO VISIT AFRICA 聯合國教科文組織領導人將出訪非洲 要注意，下面一些結構中的to-不定式是作主語補語用，而不是半助動詞be to+不定式。例如下面兩句均作“最好的還在后頭”（The best is still ahead of us,in the future）解釋，其中的to come和to be均作主語補語用： The best is still to come. The best is yet to be. 還有一些結構在語法上可作不同理解，既可看作形容詞詞組作后置修飾語，也可看作關系分句的省略形式。
例如： Those likely to arrive after 7 * notify Mrs Thomas be-fore 14 March… 可能在下午7點以后到達的人需于三月十四日前通知托馬斯夫人…… In desperation it（指her mind）lit upon the figure of her father al-ready broken in health and now about to die. 在絕望中，她腦海里突然出現了她那早已病魔纏身，如今已奄奄一息的父親的。
二、半助動詞是什么啊,舉個例子
The boy has to make a living by begging.
男孩不得不通過乞討維持生計。
He is unwilling to help me with my English.
他不愿幫我學習英語。
Every clause is obliged to obtain a finite verb.
每個句子必須包括一個限定動詞。
We were about to start when it rained.
下雨時，我們即將出發。
He seems to be very disappointed.
他好像非常失望。
I don't have to buy a new house.
我不必買新房子。
He didn't seem to feel in love with her.
他好像沒有愛上她。
三、英語句子結構分析
*主語is系詞alittlekindof狀語hoped（和is一起）謂語tobeinvited補足語 *主語found謂語himself賓語tiedtothetree賓補. 一、什么叫狀語？修飾動詞、形容詞、副詞以及全句的句子成份叫狀語。
例如：Myparentsoftentellusabouttheirbitterlifeinthepast.我父母經常給我們講他們過去的苦難生活。Shestudieshard.她努力學習。
Iamverytired.我非常疲倦。二、什么可以作狀語？1.副詞：Sayagain.再說一遍。
Suddenlyitbegantorain.天突然下雨了。2.介詞短語：Pleasecomehereintheevening.請晚上來這兒。
Hewrotewitharedpencil.他用紅鉛筆寫的。3.動詞不定式（或不定式短語）：Hewenttoseeafilm.他看電影去了。
Myfatherwassurprisedtohearthenews.我父親聽到這個消息，感到驚奇。4.分詞（或分詞短語）：Hesattherereadinganovel.他坐在那兒看小說。
Thestudentswentawaylaughing.學生們笑著走開了。5.名詞：Waitamoment.等一會兒。
Itcangoalldayandallnight.它能整日整夜地走。6.狀語從句：I'llwritetoyouassoonasIgetthere.我一到那兒就給你寫信。
Hedidn'tcomebecausehehadtostayathometofinishhishomework.他沒來，因為他不得不留在家里完成家庭作業。三、狀語的分類：狀語按用途可分為：地點、時間、原因、目的、結果、條件、讓步、程度、方式、伴隨情況等幾類。
1.地點狀語：Thestudentsaredoingtheirhomeworkintheclassroom.學生們正在教室里做作業。2.時間狀語：IlearnedalotfromthepeasantswhenIlivedinthecountryside.我在農村生活時，向農民學到很多東西。
3.目的狀語：Theysetoutearlysothattheymightarriveontime.他們早點動身，以便準時到達。4.原因狀語：Shewillnotgohomebecauseshehastoattendameeting.因為要開會，所以她不能回家了。
5.結果狀語：LiMingstudiedsohardthathecaughtupwiththeothersveryquickly.李明學習如此努力，結果很快趕上了其他人。6.程度狀語：Inearlyforgotwhathehadpromised.我幾乎忘記了他答應的事。
7.方式狀語：Hecamesinginganddancing.他唱著跳著走過來。8.條件狀語：IfyouworkhardatEnglish,youwilldowellinEnglish.如果你努力學習英語，你的英語成績就會好。
9.讓步狀語：Hewenttoschoolyesterdaythoughhewasill.昨天他盡管有病，仍上學去了。10.比較狀語：LessonTwoisnotsodifficultasLessonOne.第二課不像第一課那樣難。
四、狀語的位置：一般說來狀語在句中的位置比較靈活，它可以處于句首、句中或句末。1.狀語位于句首：為了強調狀語或者為了使它與上下文緊密銜接，通常把狀語放于句首。
TomorrowIamgoingswimming.明天我要去游泳。Hereinthecinemahouse,smokingisnotallowed.在電影院這里不準吸煙的。
2.狀語位于句中：狀語在句中的位置是：（1）如果沒有助動詞，狀語就位于動詞前面。Ioftengotoseeafilm.我經常看電影。
（2）如果動詞前有一個或幾個助動詞，狀語位于第一個助動詞之后。Hehasalreadyhadhislunch.他已吃過午飯了。
（3）如果動詞是be，狀語就放在be動詞之后。Heisalwaysathome.他總是在家。
*ekindof修飾hoped作狀語，ishoped是動詞hope的一般現在時的被動語態形式，在句中作謂語。 *是過去分詞短語，在句中作賓語補足語。
