人教版八年级英语下册现在完成时讲解及
练习
现在完成时讲解
现在完成时的基本结构是助动词have/has加上过去分词(done)。在否定句中，主语后面要加上not，构成have/has not
的形式。在一般疑问句中，have/has要提到主语前面。简略答
语中，肯定回答要用Yes，后面跟主语和have/has；否定回答
要用No，后面跟主语和haven't/hasn't。
现在完成时可以表示过去发生或已完成的动作对现在的影响或结果。比如说，“I have spent all of my money (so far)”表示
现在我没有钱花了。另外，现在完成时也可以表示发生在过去某一时刻的、持续到现在的动作或状态。这时常常和for（+时间段）或since（+时间点或过去时的句子）连用。例如，“Mary has been ill for three days”表示玛丽已经生病三天了，“I have lived here since 1998”表示我自1998年以来一直住在这里。
现在完成时还有一些标志词，可以表达过去完成的动作对现在的影响。这些标志词包括already、just和yet。例如，“He has al ready got her help”表示他已经得到她的帮助，“He hasn't come back yet”表示他还没有回来。
This is the best film I have ever seen。I have never seen a better movie before.
He has never been to Beijing before。He has never had the chance to visit Beijing.
He says he has been to the USA three times already。He has had the opportunity to visit the USA on three separate ns.
So far。he has made it to Beijing without any issues。She has successfully passed her exams up until this point.
The present perfect tense is used to describe ns that began in the past and continue up until now。or may even continue into the future。We can distinguish een the n of the n and the specific time
it occurred using phrases like "for + a d of time" or "since + a specific point in the past."
Regular verbs form the past participle by adding "-ed" to the end of the base form。For irregular verbs。there is no set pattern。and they must be memorized individually.
Spread is a verb that means to extend or distribute over an area。surface。or space。The past tense and past participle of spread is spread。For example。"I spread butter on my toast this morning."
Read is a verb that means to look at and comprehend the meaning of written or printed matter by mentally interpreting the characters or symbols。The past tense of read is read。and the
past participle is also read。For example。"I read a book last night."
The AAB verb pattern is used for verbs that have the same vowel sound in the second and third form。An example of a verb that follows this pattern is beat。whose past tense and past
participle forms are both beaten。Another example is eat。which es ate in the past tense and eaten in the past participle.
The ABA verb pattern is used for verbs that have a different vowel sound in the second form than in the first and third forms。An example of a verb that follows this pattern is e。which es became in the past tense and e in the past participle.
Run。come。and bring are examples of verbs that follow the ABB pattern。Their past tense and past participle forms are ran。came。and brought。respectively.
Buy。build。and burn are examples of verbs that follow the ABB pattern。Their past tense and past participle forms are bought。built。and burnt。respectively.
Sit。stand。and catch are examples of verbs that follow the ABB pattern。Their past tense and past participle forms are sat。stood。and caught。respectively.
