loading主系表结构
一 . 何谓主系表结构：所谓主系表结构就是英语句子中的主要成分是主语、系动词和表语。
1. 主语（ Subject ）：主语是一句话的中心，表示所说的是谁或是什么，其位置一般放在句首。英语中主语一般不省略。主语主要由名词、动名词、代词或起名词作用的短语或从句来充当。例如：
Li Lei is a Chinese boy. （ Li Lei 是名词，作主语。） He is from England. （ He 是代词，作主语。）
Feeding the birds is my hobby. （“ Feeding the birds ”是动名词短语，作主语。） What she said is right. （“ What she said ”是从句，作主语。）
2. 系动词（ Link verb ）：系动词本身有一定的词义，但不能独立作谓语，必须和句子中的表语一起构成谓语。简单地说，将主语和表语联系在一起，并构成一个完整句子的动词就叫做系动词。目前学到的系动词
有 be ， feel ， look ， sound ， taste ， smell 等。例如：
This flower is beautiful. I felt very tired. You look worried. It tastes delicious.
3. 表语（ Predicative ）：表语是用来说明主语的身份、特征或状态的。表语位于系动词之后，主要由名词、代词、形容词、数词、副词、介词短语、分词（短语）或动名词（短语）不定式短语等来充当。例如：
I am fine . （ fine 是形容词，作表语） He is a boy . （ boy 是名词，作表语）
Five plus two is seven . （ seven 是数词，作表语） We are here . （ here 是副词，作表语）
He is not at home . （“ at home ”是介词短语，作表语）
My hobby is reading . （ reading 是动名词，作表语） 二 . 主系表结构的否定形式和一般疑问句形式的构成情况 （一）否定形式：
1. 主语＋ be （ is ， am ， are ） not ＋表语。 2. 主语＋助动
（ do/ does ＋ not ＋ feel/ smell/ look?? ＋表语。例如：
She is a good girl. → She is not a good girl. You look happy. → You don’t look happy. It smells bad. → It doesn’t smell bad. （二）一般疑问句形式：
1. Be （ Is / Am/ Are ）＋主语＋表语？ 2. 助动词（ Do/ Does ）＋主语＋动词原形＋表语？例如：
This girl is in Row One. → Is this girl in Row One？ She feels terrible. → Does she feel terrible？ We look excited. → Do you look excited？
请按句子后面括号内的要求改写句子：
1. Lily is American. （改为一般疑问句） 2. I am from Sichuan. （改为否定句） 3. He looks puzzled. （改为一般疑问句）
4. They feel very excited. （改为否定句） 5. I am not feeling well. （改为肯定句）
6. The news sounds very bad. （改为一般疑问句） 7. We are all here. （改为一般疑问句）
8. The food tastes delicious. （改为一般疑问句） 9. Its name is Mimi. （改为否定句） 10. I feel well. （改为否定句）
系动词专项练习（01）
一）选择填空：（28分，28分钟）
1. My brother ____ a teacher. He ____ his pupils very much.
A. is, like B. is, likes
C. are, likes D. are, like
2. A: How many days ____ there in a week?
B: There ____ seven.
A. is, is B. are, are
C. is, are D. are, is
3. I ____ tired last night.
A. became B. felt
C. looked D. am
4. Her face ____ pale（苍白）when she heard the bad news.
A. got B. is C. turned D. was
5. You ____ pale. What's wrong with you?
A. turn B. seem C. look D. become
6. The boy ____ ill today.
A. are B. is
C. be D. am
7. Which ____ bigger, the sun or the moon?
A. are B. is
C. be D. ×
8. Neither she nor I ____ a doctor.
A. am not B. am
C. are D. is
9. I ____ a worker next year.
A. am B. will be
C. be D. will
10. Her voice ____ like my mother's.
A. sounds B. sound
C. looks D. look
11. It often rains and the crops ____ fast.
A. get B. turn
C. grow D. become