请看下面的典型试题：

　　Roses need special care _____ they can live through winter.

　　A. because B. so that C. even if D. as

　　解析：通过对题干结构的分析，此题主从句部分不是因果关系，也不是让步关系，故排除A、C两项。题干的意思是：“玫瑰需要特殊的照顾，以便它们能过冬。”不难看出，从句部分是主句所表示动作的目的，是目的状语从句，因此正确答案为B。下面对中学英语中表示目的的主要方式加以归纳。

　　一、不定式结构表示目的：此时不定式的逻辑主语常常是句子的主语。

　　1. to do sth. 意为“为了做某事”，可以用在句首或句末，其否定式为not to do sth.。如：

　　This weekend party is designed to make life happy for the students. 这次周末晚会的设计是为了使学生过得愉快。

　　To make himself heard, he stood up and shouted at the top of his voice. 为了让人听见，他站起来高声讲话。

　　2. in order to do sth. 意为“为了做某事”，可以用在句首或句末，其否定式为in order not to do sth.。如：

　　James spent most of his summer vacations in the United States in order to improve his ability to speak English. 詹姆斯的大部分暑假是在美国过的,目的是为了提高他讲英语的能力。

　　In order to gain a bigger share in the international market, many state-run companies are striving to make their products more competitive. 为了在国际市场中赢得更大的份额，许多跨国公司全力以赴地使他们的产品更具竞争力。

　　3. so as to do sth. 意为“以便做某事”，这一结构既可用在句首，也可用在句末，其否定式为so as not to do sth.。如：

　　We turned all the lights off so as not to waste electricity. 我们把所有的灯都关闭，以便不费电。

　　So as to catch the first train, he got up very early. 他起得很早，以便赶上第一班火车。

　　二、从句结构表示目的，常放在主句后面，此时主从句的主语不一定一致。

　　1. so that + 从句

　　从句谓语为“can / could / may / might + 动词原形”。如：

　　We must use new methods so that we can do the job quickly and cheaply. 我们必须使用新的方法，以便我们自己尽快地、低成本地做这项工作。

　　He studied very hard this term so that he could catch up with his deskmate. 这学期他努力学习，以便能赶上他的同桌。

　　2. in order that + 从句

　　从句谓语为“can / could / may / might + 动词原形”，可以放在句首。如：

　　We sent the letter by air mail in order that it might reach them in good time. 这封信我们航空寄去，以便他们可以及时收到。

　　Let's hand in the exercises earlier in order that the teacher may have the time to correct them. 我们尽早交上练习，以便老师有时间批改。

　　3. in case + 从句 “以防万一……”

　　从句谓语为“should / might / would + 动词原形或为一般现在时”。如：

　　Take your umbrella, in case it rains /should rain. 带上伞，以防天下雨。

　　She hid her storybook in case her teacher would find it. 她把故事书藏了起来，以防被老师发现。

　　4. (for fear that) + 从句 “以免；惟恐；以防”

　　I wrote down his E-mail address for fear that I should forget it. 我记下了他的E-mail地址，以免忘了。

　　He took an umbrella with him for fear that it might rain. 他带了一把伞，以防天下雨。

　　(文/阎荣辉；英语辅导报初中教师版04~05学年第17期；版权归英语辅导报社所有，独家网络合作伙伴新浪教育，未经许可，不得以任何形式进行转载。)