$\text{1. C }$

- Dẫn chứng câu 2 dòng 1+2

$\text{2. C }$

- Dẫn chứng câu 8 dòng 5+6

$\text{3. B}$

- Dẫn chứng câu 9 dòng 6+7

$\text{4. D }$

- Dẫn chứng câu 12 dòng 11

$\text{5. C}$

- Dẫn chứng câu 13 dòng 12

$\text{46C}$

$\text{→ Trích dẫn: Good teeth help us chew our food.}$ 

$\text{47C}$

$\text{→ Trích dẫn: Unfortunately, many people wait until the have toothache before they go to dentist.}$ 

$\text{48B}$

$\text{→ Trích dẫn: Second , we should brush our teeth with a toothbrush and fluoride toothpaste at leat twice a day - once after breakfast and once before we go to bed.}$ 

$\text{49D}$

$\text{→ Trích dẫn: Chocolate , sweets , biscuits and cakes are bad, especially when we eat them between meals.}$ 

$\text{50C}$

$\text{→ Trích dẫn: They are harmful because they stick to our teeth and cause decay.}$ 

$\text{Học tốt!!!}$