Cho các amin công thức cấu tạo như sau:

(3) CH3 - CH2 - CH2 - NH2 

(4) CH3 - CH2 - NH - CH3

Isopropylamin là danh pháp gốc chức của amin nào?

A. (4).

B. (3). 

C. (1). 

D. (2)

ĐIỀN TỪ

Chọn 01 lựa chọn đúng trong 04 lựa chọn cho sẵn để điền vào chỗ trống trong đoạn văn

It can take a long time to become successful in your chosen field, however talented you are. One thing you have to be (1) _______ of is that you will face criticism along the way. The world is (2)_________ of people who would rather say something negative than positive. If you’ve made up your (3)_______ to achieve a certain goal, such as writing a novel, (4)_________ the negative criticism of others prevent you from reaching your target, and let the constructive criticism have a positive effect on your work. If someone says you’re totally in the (5)______ of talent, ignore them. That’s negative criticism. If (6), __________, someone advises you to revise your work and gives you a good reason for doing so, you should consider their suggestions carefully. There are many film stars (7)__________ were once out of work . There are many famous novelists who made a complete mess of their first novel – or who didn’t, but had to keep on approaching hundreds of publishers before they could get it (8) ________. Being successful does depend on luck, to a (9)________ extent. But things are more likely to (10) ________ well if you persevere and stay positive.

Chọn 01 lựa chọn đúng trong 04 lựa chọn cho sẵn đề điền vào chỗ trống số (7)

A. which

B. whom

C. they

D. who

Câu 1:

a) = \(\dfrac{-7}{2}\) x \(\dfrac{45}{32}\) = \(\dfrac{-315}{64}\)

b) = \(\dfrac{18}{7}\) : \(\dfrac{-27}{14}\) = \(\dfrac{18}{7}\) x \(\dfrac{14}{-27}\) = \(\dfrac{-4}{3}\)

c) = \(\dfrac{-3}{8}\) x ( \(\dfrac{5}{11}\) + \(\dfrac{6}{11}\) + 2 ) = \(\dfrac{-3}{8}\) x 3 = \(\dfrac{-9}{8}\)

Câu 2:

\(\dfrac{-3}{5}\) . x + \(\dfrac{7}{6}\) = \(\dfrac{5}{4}\)

\(\Leftrightarrow\) \(\dfrac{-3}{5}\) . x = \(\dfrac{5}{4}\) - \(\dfrac{7}{6}\)

\(\Leftrightarrow\) \(\dfrac{-3}{5}\) . x = \(\dfrac{1}{12}\)

\(\Leftrightarrow\) x = \(\dfrac{1}{12}\) : \(\dfrac{-3}{5}\)

\(\Leftrightarrow\) x = \(\dfrac{-5}{36}\)

Để tạo ra các giống thuần chủng mang các đặc tính mong muốn (tính kháng thuốc diệt cỏ, kháng sâu bệnh, tính chịu lạnh, tính chịu hạn ), người ta thưởng sử dụng phương pháp

A.  Dung hợp tế bào trần

B. Nuôi tế bào tạo mô sẹo

C. Tạo giống bằng chọn lọc dòng tế bào xoma có biến dị

D. Nuôi hạt phấn hoặc noãn chưa thụ tinh