Khi phun thuốc trừ sâu, người ta nhận thấy sau vài lần số lượng sâu chết giảm xuống. Giải thích nào sau đây hợp lý nhất?

A. Khi phun thuốc trừ sâu đã gây nên hiện tượng kháng thuốc.

B. Sự kháng thuốc tăng lên sau nhiều lần phun.

C. Khi phun thuốc trừ sâu đã gây nên sự mẫn cảm với thuốc.

D. Sâu có thể tránh tiếp xúc với thuốc sau nhiều lần phun.

Ở đậu hà lan, alen A quy định thân cao trội hoàn toàn so với alen a quy định thân thấp; alen B quy định hoa đỏ trội hoàn toàn so với alen b quy định hoa trắng, các gen này nằm trên các NST thường khác nhau. Biết rằng không xảy ra đột biến, theo lý thuyết, trong các phép lai sau, phép lai nào cho đời con có số cây thân thấp, hoa đỏ chiếm tỉ lệ 25%?

A. AaBb × Aabb.

B. AaBB × aaBb.

C. Aabb × aaBb.

D. aaBb × aabb.

Quá trình thoát hơi nước không có vai trò nào sau đây?

A. Là động lực đầu trên của dòng mạch gỗ.

B. Tạo điều kiện cho CO₂ khuếch tán vào lá để thực hiện quá trình quang hợp.

C. Cung cấp nguyên liệu cho quá trình quang hợp và hô hấp diễn ra với tốc độ bình thường.

D. Làm giảm nhiệt độ của bề mặt lá vào những ngày nắng nóng, đảm bảo cho quá trình sinh lý diễn ra bình thường.

Bán kính hình tròn B gấp 3 lần bán kính hình tròn A. Nếu hình A lăn xung quanh hình B, nó phải thực hiện bao nhiêu vòng quay để trở lại điểm xuất phát?

1. When I was young, I wanted to become a famous -------- and work with
all the top models in Paris and Milan.
A. computer programmer
B. fashion designer
C. shop assistant
D. electrical engineer
2. Can you fix my printer for me? My office is ------ the third floor. The
printer is ------- to my desk.
A. on/next B. in/opposite C. at/next D. on/on
3. They ------- billions of dollars in the last decade in order to build mines
and get the oil out of the ground.
A. spend B. have spent C. spent D. had spent
4. Can you help me to ----- some -----? There are clothes on the floor and
the dishes need washing.
A. make/house work B. do/homework C.
do/housework D. do/favour
5. We would like to recruit three people for the positions of sales
representative. Email info@hgmsales.com for a(an) ----------- form and
a full job description.
A. applicant B. contact details C. salary D.
application
6. The windows go transparent on buildings --------the sun shines brightly
and this will save on lighting bills.
A. who B. which C. where D. that
7. Jane: What social networking site are you using?
James: I’ve just ------ an account on Weibo. Facebook will be banned
in Vietnam, I guess.
A. searched B. subscribed C. uploaded D. set up
8. ------------ I get home, my cats usually ------ and rub their heads against
my feet.
A. When/come B. If/will come C. If/would come D.
When/would come
9. Peter: ---------------------------------
Tom: Just press the red button. You’ll see the screen appear right away.
A. What happens if I press this button?
B. How do you switch it on?
C. Why do you need to do that?
D. What is this for?
10. I don’t have a degree or anything like that, but I have learned lots of --
------ on the job.
A. qualifications B. timetable C. skills D. subjects
11. The school newsletter -------- until next week, so we don’t know the
new term dates.
A. doesn’t publish B. isn’t published C. will publish
D. will be published
12. A few years ago, the stone ---------- near to the old capital of an
ancient people called the Olmec.
A. discover B. discovered C. is discovered D. was
discovered
13. My family always ------------for celebrations and during the holidays.
A. get together B. pick up C. get along D. take away
14. Let me take your details and I’ll keep the place for you until the
weekend. -------, I’ll confirm it.
A. It’s very easy
B. After we’re received payment
C. To enrol
D. You can go online
15. The Outdoor Store can supply all your ----------- needs this summer
with high quality tents, cooking equipment and sleeping bags.
A. cruise B. catering C. camping D. sightseeing
16. Before I visited northern Norway, I --------- to many parts of the world,
including the southernmost point of Patagonia.
A. have been B. had been C. went D. have gone
17. On a clear day at the top, you get a spectacular view of the whole
mountain range. It has ----- views.
A. ancient B. unforgettable C. stunning D. legendary
18. Lots of people are ------- by the ride on rollercoasters at theme parks.
A. frightened B. frightening C. interested D. interesting
19. Engineers in the nineteenth century built these -------so barges could
carry goods on water from the factories to the cities.
A. canals B. tunnels C. subway station D. avenues
20. Passenger: Can you tell me --------------------------?
Ticket clerk: In about half an hour.
A. which train do I take to the city centre
B. which train I take to the city centre
C. what time does the next train leave
D. when the next train leaves
21. We ------------ take a holiday as a family because my parents were
always working.
A. usually B. used to C. didn’t used to D. didn’t use to
22. The archaeologists -------- this object was very important.
A. say B. said C. tell D. told
23. Go outside and do -------- interesting instead of watching TV all the
time.
A. something B. anything C. everyone D. somewhere
24. Unemployment, lack of education and crime are typical examples of --
------- problem.
A. economic B. natural C. social D. traditional