29.系动词的用法]
系动词亦称联系动词(Link Verb)，作为系动词，它本身有词义，但不能单独用作谓语，后边必须跟表语(亦称补语)，构成系表结构说明主语的状况、性质、特征等情况。 说明： 有些系动词又是实义动词，该动词表达实义时，有词义，可单独作谓语，例如： He fell ill yesterday. 他昨天病了。(fell是系动词，后跟补足语，说明主语情况。) He fell off the ladder. 他从梯子上摔下来。fell是实义动词，单独作谓语。 1)状态系动词 用来表示主语状态，只有be一词，例如： He is a teacher. 他是一名教师。(is与补足语一起说明主语的身份。) 2)持续系动词 用来表示主语继续或保持一种状况或态度，主要有keep, rest, remain, stay, lie, stand, 例如： He always kept silent at meeting. 他开会时总保持沉默。 This matter rests a mystery. 此事仍是一个谜。
3)表像系动词 用来表示"看起来像"这一概念，主要有seem, appear, look, 例如： He looks tired. 他看起来很累。 He seems (to be) very sad. 他看起来很伤心。 4)感官系动词 感官系动词主要有feel, smell, sound, taste, 例如： This kind of cloth feels very soft. 这种布手感很软。 This flower smells very sweet. 这朵花闻起来很香。 5)变化系动词 这些系动词表示主语变成什么样，变化系动词主要有become, grow, turn, fall, get, go, come, run. 例如： He became mad after that. 自那之后，他疯了。 She grew rich within a short time. 她没多长时间就富了。 6)终止系动词 表示主语已终止动作，主要有prove, trun out, 表达"证实"，"变成"之意，例如： The rumor proved false. 这谣言证实有假。 The search proved difficult. 搜查证实很难。 His plan turned out a success. 他的计划终于成功了。(turn out表终止性结果)
27.虚拟语气的用法]
26.备注：强调谓语]
强调句子的谓语,要在谓语动词前加助动词do,does,did,谓语动词用原形
25.as while when的区别]
when引导暂短性动作，也可以引导持续性动作，可用于主。从句动作同时发生或从句动作先发生
eg: When I lived there, I used to go to the seashore on Sunday.
while侧重动作同时发生
While I WAS WRITING,YOU WERE TALKING WITH OTHERS
as引导持续动作，主句伴随从句动作“一边。。。一边”
He looked behind as he went
7. Any driver _______ a license ought to be punished.
A. doesn't have B. having no C. has not D. not having
Key: 1-4 DBCC 5-7 BAD
6. It rained heavily, _______ severe (严重的) flooding in the country.
A. causing B. to cause C. caused D. being caused
5. _______ the idiom, he looked it up in the dictionary.
A. Not learning
B. Never having learned
C. Having learned
D. Having been learned
4. _______ your homework, you mustn't listen to the music.
A. When do B. When to do C. When doing D. When you doing
3.The visiting minister expressed his satisfaction with the talks, _______ that he had enjoyed his stay here.
A. having added B. to add C. adding D. added