Hai chất: 2-metylpropan và butan khác nhau về

A. công thức cấu tạo

B. công thức phân tử

C. số nguyên tử cacbon

D. số liên kết cộng hóa trị

As William Chopik, associate professor of psychology and author of the study says: “Friends are a conscious choice. Family relationships can be serious, negative and monotonous." The research included two studies - one a broad survey of nearly 300,000 people, aged between 15 and 99, from more than 90 countries. This study found that those (25) ______valued friendships highly were healthier and happier (according to their own reports), especially as they got older. The second study used data from a US survey of 7,481 people over 50. Subjects were questioned about the quality of their friendships - how much friends understood them and how much they let them down.

        When friendships were reported as being stressful, people reported (26) ______        rates of disease. When friends were supportive, people were healthier. Most of the friendships were reported as being supportive. Family, (27) ______, were found to have little influence on an individual's health and wellbeing. Spouses and children had some effect, but not as much as friends.

Chopik says he isn't suggesting we ignore our families, but that friends make us feel better. With friends you are more likely (28) ______do activities - they provide an outlet. You can say things to friends and they are less judgmental. There is a distance there that provides a level of honesty." He says that cultivating good-quality friendships across our lives is beneficial - raising self-esteem and (29) ______against stress.

Điền vào số (25)

A. whom    

B. who        

C. whose     

D. which

-Về khí hậu

Đại bộ phạn lãnh thổ châu âu có khí hậu ôn đới , phần nhỏ phía bắc có kiểu hàn đới , phía nam có khí hậu địa trung hải

-Về sông ngòi

Sông ngời dày đặc có lượng nước mưa dồi dào . Nhưng 1 số cn sông lại bị đóng băng vào mùa đông

-Về thực vật

Thay đổi từ tây sang đông như: rừng lá kim , rừng lá cứng , .............

Xác định số oxi hóa của các nguyên tố trong các hợp chất, đơn chất và ion sau:

H2S, S, H2SO3, H2SO4