3.不定式作表語

　　不定式作表語時，主語通常是一個名詞，不定式短語或者從句。

　　The boss‘s plan is to start building the skyscraper immediately. to work means to earn a living. what you have to do is to push the button.

　　4.不定式作定語

　　不定式作定語相當于一個定語從句，它修飾以下幾類名詞：

　　(1)由動詞派生或轉化而來的名詞，它們所對應的動詞通常有不定式作賓語。

　　Another attempt to climb the mountain will be made next month. in his speech he expressed his determination to achieve the goal. 這類名詞主要有：attempt， claim， decision， plan， promise， intention， need， resolution，tendency， wish， failure， threat等。

　　(2)由可能與不定式搭配的形容詞派生出來的名詞。

　　Her eagerness to learn a foreign language obvious.這類名詞主要有：anxiety， patience， ability， willingness， ambition等。

　　(3)不定式作定語還可用來修飾代詞something， anything， everything， nothing.

　　she has everything to lose and nothing to gain.

　　(4)由only， last， next， 序數詞或形容詞最高級修飾的名詞后常用不定式作定語。

　　Jim is the only student to answer the question correctly in his class. you are the last to undertake the blood test.

　　(5) 不定式常作為定語修飾there be結構的真實主語。

　　There is a big task to complete.

　　(6) 有些抽象名詞。主要有：reason， right， time， effort， chance， way等。如： the time to go to school， the way to get to the clinic， the chance to win the game.

　　5.不定式作狀語

　　不定式作狀語相當于一個狀語從句，表示形為的目的、結果或原因。

　　(1)表示目的。在這種情況下，不定式的邏輯主語通常也是全句的主語。

　　He stayed there to see what would happen.在強調不定式目的狀語時，不定式前可加in order， so as等。如：

　　She asked me to drive her to the airport in order to catch the 5： 00 plane. he moved the tv set to the meeting-room so as to let everyone watch it.

　　(2)用so……as to……， such （……） as to……， enough to……， too……to， only to等表示結果，如：

　　Have you got enough room to seat all of us？

　　She is too weak to join us in the outing.