$\text{1.}$ C

$\text{→}$ Dòng 1, đoạn 1: Good teeth have us chew our food.

$\text{2.}$ C

$\text{→}$ Dòng 3, 4; đoạn 1: This happens after germs and bit of food have collected there. Then the decay slowly spreads inside to the tooth.

$\text{3.}$ B

$\text{→}$ Dòng 1, 2; đoạn 2: First, we ought to visit the dentist twice a week. He can fill the small holes in our teeth before they destroy the teeth.

$\text{4.}$ D <mik nghĩa là A và C>

$\text{→}$ Dòng 1, 2; đoạn 3: Secondly, we should brush our teeth with a toothbrush and fluoride toothpaste at least twice a day - once after the breakfast and once before we go to bed.

$\text{→}$ should = ought to

$\text{5.}$ D

$\text{→}$ Dòng 1, 2; đoạn 4: Thirdly, we should eat food that is good for out teeth and our body: milk, cheese, fish, brown bread, potatoes, red rice, raw vegetables, and fresh fruits.

$\text{→}$ 3 từ đầu là nên ⇒ từ cuối là ko nên

1.C(good teeth helps us to chew our food.)

2.C( The decay begins in a little crack in the enamel covering of the tooth)

3.B( He can fill the small holes in our teeth before they destroy the teeth)

4.D( we should brush our teeth with a toothbrush and fluoride toothpaste at least twice a day – once after breakfast and once before we go to bed)

5.D(Chocolate, sweets, biscuits and cakes are bad, especially when we eat them between meals)

5* và ctlhn nhé