Complete the sentences with the past simple and the present perfect: 21. she(catch) a cold last monday.22. they(not / buy) a new computer yet.23.i(just/help) my little brother to draw a horse.24. granny(bake) apple pies last wednesday.25. she(already / wash) her skirtmake) a cake before.26. sheila and elsa(make) a cake before ​

ответ:

21 caught

22 haven't bought

23 have just helped

24 baked

25 has already washed

26 have made

объяснение:

51a.

1 have to

2 had to

3 need

4 have to

5 need

6 must

51b

1 has to buy

2 have to find

3 must to go

4 Do we need to leave

5 must to clean

6 Did you have to pay

45a

1 Bob wasn't able to read until he was six.

2 We are able to see the sea from our window.

3 Not many people are able to drive a bus.

4 We were able to speak to them in English.

5 They weren't able to dance or sing.

6 I didn't able to understand the film.

52a

1 mustn't swim

2 aren't allowed to speak

3 mustn't touch

4 couldn't enter

5 can't use

6 aren't allowed to smoke

53a

1 a

2 f

3 e

4 d

5 b

6 c

1. higher

2. dirtier

3. more dangerous

4. better

5. thinner

6. slower

7. healthier

8. futher

9. more comfortable

10. worse

Объяснение:

в данной группе слов были как односложные прилагательные (1,2,5,6,7), которые образуют сравнительную/превосходную степень по правилу (путём добавления суффикса -er, -est), так и многосложные (3, 9), к которым нужно всего-то подставить слово more/the most для образования сравнительной и превосходной степеней сравнения соответственно.

остальные же (4,8,10)-исключения и никакому правилу не поддаются. учить..