Complete the following sentences using appropriate conjunctions or relative pronouns.

Here are the solutions to the English grammar questions:

Question 9:
You should either apologize or face the consequences.
$\boxed{\text{Either...or}}$

Question 10:
Rajesh is intelligent and hardworking.
$\boxed{\text{and}}$

Question 11:
The train was late, so we missed our appointment.
$\boxed{\text{so}}$

Question 12:
Aadhya speaks English and French.
$\boxed{\text{and}}$

Question 13:
The coffee was hot, so I couldn't drink it immediately.
$\boxed{\text{so}}$

Question 14: (Unnumbered, follows Q13)
You should work harder, otherwise you will fail the test.
$\boxed{\text{otherwise}}$

Question 15: (Unnumbered, follows Q14)
The book was thick, but I finished reading it in one day.
$\boxed{\text{but}}$

Question 16: (Unnumbered, follows Q15)
This is the boy who won the race.
$\boxed{\text{who}}$

Question 17: (Unnumbered, follows Q16)
Mohan is a musician whose concert was amazing.
$\boxed{\text{whose}}$

Question 18: (Unnumbered, follows Q17)
You must either tell the truth or face the punishment.
$\boxed{\text{Either...or}}$

Question 19:
Eesha completed her homework and went to play outside.
$\boxed{\text{and}}$

Question 20:
You can either stay here or leave immediately.
$\boxed{\text{Either...or}}$

Question 21:
Charvi was tired, so she went to bed early.
$\boxed{\text{so}}$

Question 23:
Garima is neither interested in studying nor in working.
$\boxed{\text{neither...nor}}$

Question 24:
We can either go to the park or go to the beach.
$\boxed{\text{Either...or}}$

Question 25:
Niraj Chopra is the athlete whose training is intense.
$\boxed{\text{whose}}$

Question 26:
The provided options (Either...or, neither...nor) are not suitable for combining these sentences, which express a contrast. A conjunction like "but" would be appropriate.

Question 27:
Although it was expensive, she bought the dress.
$\boxed{\text{although}}$

Question 28:
The provided options (Either...or, neither...nor) are not suitable for combining these sentences, which express a contrast. A conjunction like "but" would be appropriate.