Nguyên nhân của hiện tượng bất thụ ở cơ thể lai xa chủ yếu là do

A. sự không phù hợp giữa nhân và tề bào chất của hợp tử.

B. hai loài bố mẹ có số lượng và hình thái NST khác nhau.

C. sự không tương hợp giữa hai bộ gen ảnh hưởng tới sự bắt cặp của các NST trong giảm phân.

D. bộ NST ở con lai là số lẻ ví dụ như lừa cái lai với Ngựa đực tạo ra con La (2n = 63).

Mark the letter A, B, C, or D on your answer sheet to show the underlined part that needs correction in each of the following questions.

It is often said(A)  that the British talks(B) about the weather more than(C) any other people(D)  in the world.

A. often said

B. talks

C. more tha

D. ther peopl

Read the following passage and mark the letter A, B, C or D on your sheet to indicate the correct word or phrase that best fits each of the numbered blanks from 36 to 46

I was with Overseas Volunteers (OV) for a year after leaving university, and I was sent to an isolated village in Chad, about 500 kilometres from the capital N’Djamena. Coming from a (36)______country, I got quite a shock, as conditions were much harder than I had ( 37) ______. But after a few days I soon got used to (38) ______there. The people were very friendly and helpful, and I soon began to appreciate how beautiful the countryside was.

One of my job was to supply the village with water. The well was a long walk (39) _____, and the women used to spend a long time every day ( 40)_______heavy pots backwards and forwards. So I contacted the organization and arranged to (41 ) _____some pipes delivered. We built a simple pipeline and a pump, and it worked first time. It wasn’t perfect there were a few (42) _____but it made a great difference to the villagers, (43 )______had never had running water before. And not (44 ) ____did we have running water, but in the evenings it was hot, because the pipe had been (45) ____ in the sun all day.

All in all, I think my time with OV was a good experience. I would recommend it to anyone who was planning to work for a charity

Điền vào ô 44

A. hardly

B. scarcely

C only

D. also

Trong hệ sinh thái, bậc dinh dưỡng nào sau đây dễ bị tuyệt chủng hơn các bậc dinh dưỡng còn lại?

A. Bậc dinh dưỡng thứ 2

B. Bậc dinh dưỡng thứ 4

C. Bậc dinh dưỡng thứ nhất

D. Bậc dinh dưỡng thứ 3