1.He said to me :"What is the name of your school?" 2. Mrs.Jackson said to Tim "You must improve his Spanish pronunciation " 3.The doctor said to Nam "You have to to eat fatty food" 4. The examiner said to me"What aspect of learning English đó you find most difficult?" 5. She asked me "Is your school near here?" 6.Mary said "This birthday cake is delicious"

Bài 4. Nguyên tử của một số nguyên tố có số hiệu nguyên tử là : 11,15,16,19,20. Nêu vị trí và cấu tạo của các nguyên tố này.