Let's analyze each blank and fill in the best answer along with explanations:

1. **(1)** A. **wearing**
- Correct answer: A. wearing
- Explanation: The phrase "objected to" is typically followed by a gerund (verb + -ing), making "wearing" the correct choice.

2. **(2)** B. **keen on**
- Correct answer: B. keen on
- Explanation: "Keen on" is the correct phrase to indicate enthusiasm about something.

3. **(3)** A. **the same**
- Correct answer: "the same" (this should be based on options found in a complete list, but it's implied as the most common phrase).
- Explanation: The context suggests that the teachers wanted all students to look uniform or similar.

4. **(4)** C. **with**
- Correct answer: "with" (again, inferred based on the context).
- Explanation: The children completing with each other suggests they would compete in fashion rather than academics.

5. **(5)** C. **how poor they are**
- Correct answer: C. how poor they are
- Explanation: "how poor they are" is the grammatically correct way to express the state of being poor.

6. **(6)** D. **given up**
- Correct answer: D. given up
- Explanation: "given up" implies that many schools have abandoned the idea of uniforms.

7. **(7)** A. **wear**
- Correct answer: A. wear
- Explanation: The simplest form of the verb "wear" follows "making children".

8. **(8)** C. **what**
- Correct answer: C. what
- Explanation: "what they like" suggests an open choice of clothing.

9. **(9)** B. **a uniform of their own**
- Correct answer: B. a uniform of their own
- Explanation: This option accurately reflects the idea of the children’s own style of uniform.

10. **(10)** Should be based on context (not provided).
- A setting such as a school or a classroom would fit.

11. **(11)** C. **in**
- Correct answer: C. in
- Explanation: "dressed in jeans" is the correct phrasing for describing clothing.

12. **(12)** **rather** (Context suggests filling with 'would' or 'not' based on the provided sentence).
- Context-dependent, but "would rather" fits.

13. **(13)** B. **no one**
- Correct answer: B. no one
- Explanation: "no one wants to look different" fits the construct appropriately.

14. **(14)** **than** (Context inferred).
- Correct form suggests comparison, "than" is the right choice here.

15. **(15)** **might** (could either use 'might' or 'may').
- Context suggests feelings of uncertainty in parents.

16. **(16)** B. **seem** or **appear** (Context requires a verb).
- Needs a verb suggestion.

17. **(17)** **what** (needs context for filler)
- Could be filled with a descriptor, like "that".

18. **(18)** B. **they have been forced**
- Correct answer: B. they have been forced
- Explanation: "they have been forced" is the right grammatical structure.

19. **(19)** **better**
- Correct answer: "better"
- Explanation: Comparative "better than".

20. **(20)** A. **used to be**
- Correct answer: A. used to be
- Explanation: "used to be" indicates something that was true in the past but is no longer the case.

To summarize:
1. A. wearing
2. B. keen on
3. the same
4. with
5. C. how poor they are
6. D. given up
7. A. wear
8. C. what
9. B. a uniform of their own
10. (Needs context)
11. C. in
12. would (rather)
13. B. no one
14. than
15. might
16. seem
17. (Needs context)
18. B. they have been forced
19. better
20. A. used to be

These results can help in understanding the correct usage and structure in English language context.