系动词为be动词
(一)第一句型：主语 系动词 表语 1) 系动词一般为be 动词。
注意：look， feel， sound， smell， taste， get， become， come， go， turn， grow， keep， seem， stand等词可以作"半系动词"用，按行为动词方式变化，起系动词的作用。
试验比较：
—— He felt the pockets thoroughly but did not find a single penny.(他摸遍了口袋但没有找到一分钱。—— feel为行为动词)
—— You look pale. Do you feel unwell？ (你脸色苍白，感到不舒服？—— look / feel为系动词)
一般来说，动词后面跟的是个形容词或名词，该动词为系动词， 如：The plan sounds perfect. / The flower smells nice. / The dish tastes delicious. / It is getting dark.
实例：
"Dont worry. Let me take your pulse first." "Oh， it ______ normal." (脉搏正常)
A. is felt
B. is feeling
C. feels
D. felt
解题思路：normal为形容词，前面应为系动词；系动词没有被动语态，故A不对； look， feel， sound， taste， smell， seem等半系动词一般不用进行时，B也不对；D时态错了，故正确答案为C.
2)there be是英语中非常重要的一个句型： there是引导词，不解释 "那里"； 这是个倒装句， 主语在be动词的后面， be动词的单复数由后面的主语决定。
注意中国学生容易搞错的问题： There isnt enough furniture in the room.(房间里家具不够)
错：There hasnt enough furniture in the room.
There is no doubt that smallpox has been wiped out in China.(毫无疑问，中国已消灭天花。)
错：It is no doubt that smallpox has been wiped out in China.
There is ample evidence that AIDS is spreading quickly in Asia. (充分证据表明，爱滋病正在亚洲迅速蔓延。—— 同位语从句)
错：It is evidence that AIDS is spreading quickly in Asia. (可以： It is evident that AIDS is spreading quickly in Asia. - 主语从句)