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【考點點撥】 在復(fù)合句中，用作狀語的從句叫做狀語從句,。狀語從句有下列幾種類型： 注意：在含有時間或條件狀語從句的復(fù)合句中，如果主句用一般將來時,，從句通常用一般現(xiàn)在時表示將來,。 if引導(dǎo)的條件狀語從句if意為“如果”，由if引導(dǎo)的條件狀語從句,，可以放在主句后,，也可以放在主句前；當(dāng)從句放在主句前時,，常用逗號與主句隔開,。條件狀語從句表示主句動作發(fā)生的前提、條件等,。 在含if引導(dǎo)的條件狀語從句的復(fù)合句中,，從句的時態(tài)通常遵循以下規(guī)則： ◆當(dāng)主句為一般將來時態(tài)時，從句用一般現(xiàn)在時,。如： I will go with you if it doesn’t rain tomorrow. ◆當(dāng)主句的謂語含有can, may, must等情態(tài)動詞時,，從句用一般現(xiàn)在時,。如： You can watch TV if you finish your home-work. ◆當(dāng)主句是祈使句時，從句用一般現(xiàn)在時,。如： Don’t forget to turn off the lights if you leave the office. 溫馨提示：“unless+肯定句”相當(dāng)于“if+否定句”,。如： You will fail unless you study hard. = You will fail if you don’t study hard. until, although, so that引導(dǎo)的狀語從句在復(fù)合句中，用作狀語的從句叫狀語從句,。until引導(dǎo)時間狀語從句,，用于肯定句時，意為“直到……為止”,，主句中的謂語動詞用延續(xù)性動詞,；用于否定句時，意為“直到……才……”,，主句中的謂語動詞用非延續(xù)性動詞,。 although引導(dǎo)讓步狀語從句，意為“盡管,；雖然”,通?？梢耘cthough互換使用，但二者都不能與but同時出現(xiàn)在一個句子中,。 so that引導(dǎo)目的狀語從句,，從句中的謂語動詞一般和can, could, may, might等情態(tài)動詞連用。 unless, as soon as, so…that引導(dǎo)的狀語從句◆unless意為“除非,；如果不”,，引導(dǎo)條件狀語從句，常?？梢院蚷f … not句型互換,。如： I won’t let you in unless you show me your pass. = I won’t let you in if you don’t show me your pass. 如果你不出示通行證，我不會讓你進(jìn)去,。 ◆as soon as意為“一……就……”,，引導(dǎo)時間狀語從句，表示從句的動作一發(fā)生,，主句的動作馬上發(fā)生,，強(qiáng)調(diào)動作的緊密性。如：I will call you back as soon as I arrive. 我一到就給你回電話,。 ◆so … that …意為“如此……以至于……”,，so … that引導(dǎo)結(jié)果狀語從句，so作副詞,，后接形容詞或副詞,，that后接從句。如：The wind was so strong that we could hardly move forward. 風(fēng)太大了，我們簡直寸步難行,。 She spoke so quietly that I could hardly hear her. 她說話輕得我?guī)缀趼牪灰姟?/p> 【經(jīng)典習(xí)題】1. —Your English is so good. How long have you been in England? — I was six. A. Until B. Since C. When D. Before 2. —Would you like to go swimming with us tomorrow? —Of course, I am busy. A. unless B. if C. although D. Because 3. The old lady gave lots of money to the poor students, she is not rich. A. when B. as soon as C. if D. Though 4. we don’t protect the earth, we will have no clean water to drink. A. Until B. Though C. If D. Before 5. —Where was your brother at this time yesterday? —He was reading a book I was watching TV at home. A. as soon as B. while C. until D. after KEY: 1-5 BADCB |
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