một gen nhân đôi 3 lần và đã sử dụng của môi trường  21000 nucleotit tự do số nu của gen bằng

23.Bob said ,” I have always wanted to take part in th English speaking competition .”

-> Bob has always dreamed……………………………………………

24.Bob said ,” I heard you have got good marks . Congratulation , Mary .”

-> Bob congratulated……………………………………………

25.”Don’t stay at the hotel near this airport ,” I said to Ann

->I warned……………………………………………………………………

26.” I will drive you  to the station. “ Peter said-> Peter insisted………………………………………………

27.He says’’ I will pick you up at 8 am tomorrow’-> He says ………….……………………………………….

5. Mary started going to work by her own car last Friday.

=Mary has ..............................

6. My grandpa started to test  his eyes  ten months ago.

= My grandpa ……………………………………….

7.They began to cook dinner 20 minutes ago

=They…………………………………………….

3. It is three years since I saw Rose.

=The last time …………………………………….

=I haven’t…………………………………………..

=I last………………………………………………….

4.It's ages since Tom last saw a Hollywood film.

=Tom has……………………………………………..

=Tom last………………………………………………..

=The last time……………………………………………….

5.The last time I went to the museum was a year ago.

a. I have not been to the museum for a year.

b. A year ago, I often went to the museum.

c. My going to the museum lasted a year.

d. At last I went to the museum after a year.

6. I have not met her for three years.

a. The last time I met her was three years ago.

b. It is three years when I will meet her.

c. I did not meet her three years ago.

d. During three years, I met her once.

7. I began to eat this pasta last week.

a. I used to eat this pasta last week.

b. I have eaten this pasta for last week

c. It is the first time I ate this pasta.

d. I have eaten this pasta since last week.

8.     I have not seen Tom for ages.

a. It ‘s a long time since I last saw Tom.

b. Tom and I do not look the same age.

c. Tom and I are friends for a long time.

d. I often met Tom ages ago.

7. I will graduate after I (see) _have seen_________ you .

9. It probably will rain when we (arrive) ___have arrived_______ in London tonight.

10.Lan wil come home after she (finish)_has finished_________her project.

11.When Bob( arrive)_____, he will tell us about the match.

12.Before the head teacher ( arrive )_______, I will give the guests their tea.

13.As soon as I ( finish )_______, I will give you call.

14.Can you look after the children while I ( be )______ out ?

15.When I ( read )_______ this novel, you can have it.

16.Peter and John are going to play tennis tonight. While they ( play )_______-,we will go to the beach.

y = x-1+1/x
tính y' , xác định khoảng  đồng biến và nghịch biến

: Xà phòng hóa 6,6 gam etyl axetat bằng 200 ml dung dịch NaOH 0,2M. Sau khi phản ứng xảy ra hoàn toàn, cô cạn dung dịch thu được chất rắn khan có khối lượng là  

A. 3,28 gam.         B. 8,56 gam.          C. 8,2 gam.           D. 10,4 gam.

Phát biểu nào sau đây là sai?

          A. Ở điều kiện thường, chất béo (C₁₇H₃₃COO)₃C₃H₅ ở trạng thái rắn.

          B. Chất béo là tri este của glixerol với axit béo.

          C. Metyl acrylat, tripanmitin và tristearin đều là este.

          D. Thủy phân hoàn toàn chất béo luôn thu được glixerol.