九、作形式主語
(一)、替代動詞不定式
It is + adj. to do sth.
83. It is good to eat vegetables.
84. It is an honor to have been asked to speak at themeeting.
It is + adj. +for sb. to do sth.
注意：此結構中的形容詞是描述事情的、說明句尾動詞不定式特徵的形容詞。這些形容詞主要有certain, clear, dangerous, difficult, easy, hard, illegal, impossible, important, obvious, possible, polite, proper, right, unnecessary, unimportant, unlikely, useless, useful等。
85. She is such an eccentric woman that it is difficult for anyone to get on well with her.
86. It is a good custom for young people to give up their sets to old people in the busestrains, or subways.
It is + adj. + of + sb. to do sth.
注意：本句型中的形容詞一般表示人(邏輯主語)的某種特性，要麼是誇讚，要麼是貶損。主要有brave, careful, careless, considerable, cruel, clever, foolish, good, grateful, generous, impolite, kind, nice, polite, rude, silly, stupid, thoughtful, unkind, wise, wrong,等。
87. It is kind of you to lend me so many books.
88. It is clever of you to solve so difficult a problem.
89. It is wise of you to refuse his offer.
90. It is remarkable of her to be always working like this.
It is a pity(for sb.) to do sth. 很遺憾做某事
91. It would be a pity to miss the opening ceremony.
92. It is a pity for you not to go to Paris with us.
It is a great relief (to sb.) to do sth. 做……是一大慰藉；……真叫人送了一口氣
93. It is a great relief to have rain after a long time of drought.
94. It’s a great relief to me to know you are safe.
95. It’s a great relief to hear that she won the prize.
It is worth while to do sth. 做……是值得的
注意：本句型就相當於It pays to do sth.；worth while 不要寫成worthwhile。
96. It is worth while to take a trip abroad.
97. It is worth while to learn English.
It’s best to do sth. 最好做某事 = To do sth. is best.
98. It’s best to set off tomorrow. 最好明天動身。 = To set off tomorrow is best.
99. It’s best to review the lessons one more time. = To review the lessons once more is best.
It’s better to do A than to do B = To do A is better than to do B.
100. It is better to borrow than to buy. = To borrow is better than to buy.
101. It’s better to stay at home than to go to the cinema. = To stay at home is better than togo to the cinema.
How is it possible to do sth.? ……這怎麼可能？
102. How was it possible to fall down from the third floor without being hurt?
103. How is it possible for a girl of ten to fly an airplane?
It’s no use to do sth. 做……是沒有用的
104. It’s no use to argue with him.
105. He doesn’t know the answer, so it is no use to ask him.
It takes (sb.) + 時間/條件 + to do sth. 某人花了多少時間做某事；做某事需要……(條件)
106. It takes me half an hour to walk from here to school.
107. How long does it take to fly Being to London?
108. It takes patience and hard work to master English.
It costs sb. some money to do sth. 某人花多少金錢做某事
109. It cost him a great deal of money to take the trip.
100. It cost me 2000 dollars to collect these stamps.
It occurs to sb. to do sth. 某人突然想到做某事
111. It never occurred to me to take advantage of you. 我決沒有想到過要佔你便宜。(利用你)
It feels + adj. + to do sth.
112. It feels pleasant to talk with her. 同他談話使人感到愉快。
113. It must feel strange to have a twin brother.
114. It feels unhappy to be with him.同他在一塊讓人感到不舒服。
115. It feels nice to take a walk in the evening. 晚間散散步感覺很好。
其它例句
116. It seems a pity not to have taken his advice.
117. It won’t hurt to postpone the party for a few weeks.
118. It did surprise me to hear you say so.
119. It gave great pleasure to have finished this work ahead of the dead line.
(二)、替代動名詞
動名詞可以直接位於句首作主語，但為了強調，或動名詞過長時，要用it作形式主語置於句首，而把動名詞放到句子最後。這也是英語尾部重壓原則所要求的。
It is no good/use (in) doing sth. 做……是沒用的；做……是白費力氣的
= It is of no good/use doing sth.
= It is not any good/use doing sth.
120. It is no sue crying over spilt milk.覆水難收，悔恨無益。
121. It is no use trying to drown your sorrows in drink. 解酒澆愁無濟於事。
122. It’s no good getting cross with him.和他生氣沒有用。
123. It’s no good reading without full understanding.
It’s exciting doing sth.
124. It’s exciting meeting you here.
It’s dangerous doing sth.
125. It’s dangerous playing with fire.
It’s foolish doing sth.
126. It’s foolish behaving like that.
It’s pleasant doing sth.
127. It’s pleasant lying in the sun.
It’s fun doing sth.
128. It’s fun being a magician.
It’s no use doing sth. 做……沒有用
129. It’s no use crying over spilt milk.
130. It’s no use regretting.
131. It’s no use you running away.
注意：
1. 辨析：It’s no use doing sth. & It’s no use to do sth.
132. It’s no use doing sth. 通常指比較一般的情況。
133. It’s no use to do sth.常指具體的情況，也就是指在某一特定的場合所發生的事情。
2. 類似句型
134. It’s useless to do sth.
135. It’s of no use to do sth.
It’s a nuisance doing sth. 做……很煩人。
136. It’s a nuisance having to do so much homework.
注意：這一結構中的動名詞還可加one’s即物主代詞來充當該動名詞的邏輯主語。
137. It’s a waste of time your talking to him. It is just like casting pearls before swine.
138. It was great encouragement to us their coming to help.
139. It is useless doing that over and over again.
注意：辨析：It’s nice to do sth. & It’s nice doing sth.
140. It’s nice to do sth. 常用於見面或活動開始； It’s nice doing sth.則用於分手或活動結束。
141. It’s nice taking a walk in the evening.
142. It’s so nice sitting near a fire in winter.
143. It’s nice to meet you here.
144. It’s nice to have a talk with you. (說話開始)
145. It’s nice talking with you. （談話之後）
It’s hard doing sth.做某事有困難
146. It’s hard learning English well.
It’s interesting doing sth.做某事有趣
147. It’s interesting going sight seeing.
It’s easy doing sth.做某事容易
148. It’s easy working out this problem.
(三)、替代主語從句
句型一：It + be + adj. + that從句