单 元：Unit 1 Tales of the unexplained
Thoughts on the design:
Learn the differences between the present perfect tense and the present perfect continuous tense.
1. Learn how to form and use the present perfect tense.
2. Understand when the present perfect continuous tense is used in sentences.
procedures:
Step 1 Compare the two tenses
1. We use the present perfect tense to talk about an action completed in the recent past, and the present perfect continuous tense for an action that started in the past and is still happening.
现在完成时和现在完成进行时都表示动作从过去开始，但现在完成时可表示事件或动作刚结束，而现在完成进行时则强调动作仍在继续。
1) Li Jia has read a book about Stonehenge. （表示她已经读完了。)
2) Li Jia has been reading a book about Stonehenge. (表示她仍在读。)
2. We can use the present perfect tense for repeated actions, and the present perfect continuous tense for non-stop actions.
We usually use the present perfect tense to ask questions beginning with how many/much, and the present perfect continuous tense to ask questions beginning with how long.
现在完成时可表示反复发生的动作，提问时用how many / how much。而现在完成进行时则表示持续的、不间断的动作，提问时用how long。
1) —How many times have you visited Egypt this month? 你这个月去了埃及几次？
—I have visited Egypt twice this month. 我这个月去了埃及两次。
2) —How long have you been touring Egypt? 你在埃及旅游多久了？
—I have been touring Egypt for two months. 我已经在埃及旅游两个月了。
3. We can use either a state verb or an action verb with the present perfect tense but we usually can only use an action verb with the present perfect continuous tense.
现在完成时可以用表示状态的动词或表示动作的动词做谓语。而现在完成进行时则只能用表示动作的动词做谓语。
1) I have had this camera for five years. (had是表示“拥有”状态的动词)
2) I have taken photos of UFOs with this camera. (taken是表示动作的动词)
3) I have been taking photos of UFOs with this camera. (taking是表示动作的动词)
4. We use the present perfect tense, not the present perfect continuous tense, with the words like never, yet, already and ever.
现在完成时的句子中可以用像never、yet、already和ever这样的词，而现在完成进行时的句子中则不可以用这样的词。
Exercise:
1. “How long have you been here?”
“Only about five minutes. Henry and Simon _____ here with me.”
A. have walked B. were walking C. had walked D. Walked
2. The museum he paid a visit _____ at the end of the street.
A. stand B. stands C. to stand D. to stands
3. By the end of the 18th century, the city’s population _____ about two million.
A. was B. were C. had been D. being
4. You _____ I am right if you look into the matter from my point of view.
A. will see B. are going to see C. are to see D. are about to see
5. “What were you doing when your mother called you?”
“I had just finished writing my research paper and _____ to type it.”
A. had started B. is starting C. was starting D. has been starting
6. No wonder those flowers _____. They _____ any water for long.
A. are dying; haven’t had B. died; didn’t have
C. had died; haven’t had D. have died; hadn’t had
7. “What did George do before he retired?”
“He _____ chemistry in a middle school for twenty-five years.”
A. is teaching B. taught C. has taught D. was teaching
8. _____ to have tea in the morning?
A. Will you like B. Do you like C. Would you like D. Shall you like
9. By this time tomorrow, I _____ on the beach.
A. will lie B. am lying C. will be lying D. lie
10. Every day, in every way, I _____ better and better.
A. am getting B. get C. will get D. am going to get
11. Sir, I bought the clock here yesterday, but it _____ go.
A. didn’t B. won’t C. can’t D. doesn’t
12. It was for the first time in my life I _____ given such a beautiful present.
A. have been B. was C. had been D. be
13. At present many scientists _____ a study of intelligent beings living in outer-space.
A. make B. will make C. are making D. have made
14. It is said in the book that Thomas Edison(1847-1931)_____ the world leading inventor for sixty years. A. would be B. has been C. had been D. was
15. Don’t worry, it’ll be a bit difficult the first time you _____ the children. Soon you’ll find it much easier.
A. are seeing B. will see C. see D. have seen
