句型一主语+系动词+表语
[讲解] (1) 系动词的三种分类：在初中阶段，我们学过的表示“保持或状态”类的有be, remain, stay, keep, prove等；表示“变化”类的有grow, turn, get, become, fall, go, come等；表示“感官”类的有look, sound, smell, taste, feel, seem, appear等。例如：
I am a senior school student while he is a junior one.
我是高中生，他是初中生。
After four years, Tom became a doctor/ turned doctor.
四年后，汤姆成了一名医生。
The story sounds interesting and instructive.
这故事听起来既有趣，又有教育意义。
(2) 可以充当表语的有形容词、名词、副词(短语)、介词短语、表语从句、分词(短语)等。例如：
In order to keep healthy, he takes exercise everyday. (形容词作表语)
In my mind, mother is my hero. (名词作表语)
Look! Your pet dog is there. (副词作表语)
The schoolbags come in different sizes. (介词短语作表语)
You’ve changed a lot. You are not what you were. (表语从句作表语)
Many passengers got injured in the accident. (过去分词作表语)
The machine keeps running for a long time. （现在分词短语作表语）
(3) 使用系动词应注意的地方：第一，没有被动语态；第二，一般没有进行时(除了feel以外)；第三，有些动词既是系动词又是普通动词。如：keep, grow, taste, feel, get, smell等。第四，非谓语一般用现在分词(这一点仅作了解，高中阶段将涉及。)
例如：After two-day’s treatment, he felt well again. (不用was felt)
He remains an excellent engineer in the factory. (不用 is remained)
比较以下句子：
The pet dog keeps clean. It is kept by Johnson.
(keeps是系动词，而kept是及物动词)
We grew some trees around our school and they grow green now.
(grew是及物动词，而grow是系动词)
Just now I felt the table and it felt smooth.
(第一个felt是及物动词，而第二个是系动词)
[练习] 选择一个合适的词或根据汉语提示填空，注意动词的适当形式。
(1) I __________(remain / keep / stay) a nurse while he has __________(turn / become) engineer.
(2) Put the meat in the refrigerator (冰箱). It __________ (go / get / turn / become) bad easily.
(3) What he said __________(sound / look / smell / taste) reasonable.
(4) He feels __________(comfortable / comfortably) working in the air-conditioned office.
(5) We do morning exercises to __________(keep / turn / become) healthy.
(6) The apple __________(tastes / is tasted) sweet.
(7) Please keep __________(安静); The baby has fallen __________(睡着).
(8) They work day and night to make their dream come __________(实现).

Key:
(1) — (4) remain, turned; goes; sounds; comfortable
(5) — (8) keep; tastes; quiet, asleep; true