3. Instead of (leave) at 9, it was about 10 before they set off.
4. The hostess couldn`t help (offer) me a cup of tea. I was afraid of (upset) her. I`m not used to (drink coffee at that time of the day. But it was no use (refuse).
5. The car broke down! I normally enjoy (drive), but when things go wrong, I hate cars.
6. By the time we went out it had started (rain).
7. It`s no use (look) for the nearest phone box.
8. I was not in a very good mood because she started (offer) me advice.
9. What about (go) to the cinema tonight?
10. I`m not pleased with (do) this useless work.

3. Instead of leaving at 9, it was about 10 before they set off.
To correct the sentence, we need to change the verb "leave" to its correct form. In this case, the correct form is "leaving" because it is referring to an action that happened before another action in the past. The sentence should be: Instead of leaving at 9, it was about 10 before they set off.

4. The hostess couldn't help offering me a cup of tea. I was afraid of upsetting her. I'm not used to drinking coffee at that time of the day. But it was no use refusing.
In this sentence, we have multiple verbs that need correction. Firstly, "offer" is the correct form, not "offering." Secondly, "upset" is the correct form, not "upsetting." Thirdly, "drink" is the correct form, not "drinking." Finally, "refusing" is the correct form, not "to refuse." The corrected sentence should be: The hostess couldn't help offering me a cup of tea. I was afraid of upsetting her. I'm not used to drinking coffee at that time of the day. But it was no use refusing.

5. The car broke down! I normally enjoy to drive, but when things go wrong, I hate cars.
The verb "enjoy" should be followed by the gerund form, not the infinitive form. The corrected sentence should be: The car broke down! I normally enjoy driving, but when things go wrong, I hate cars.

6. By the time we went out, it had started raining.
The verb "start" should be followed by the gerund form, not the infinitive form. The corrected sentence should be: By the time we went out, it had started raining.

7. It's no use looking for the nearest phone box.
The verb "look" should be followed by the gerund form, not the infinitive form. The corrected sentence should be: It's no use looking for the nearest phone box.

8. I was not in a very good mood because she started offering me advice.
The verb "offer" is the correct form, not "offering." The corrected sentence should be: I was not in a very good mood because she started offering me advice.

9. What about going to the cinema tonight?
The sentence is already correct. There is no need for any corrections.

10. I'm not pleased with doing this useless work.
The verb "do" is the correct form, not "doing." The corrected sentence should be: I'm not pleased with doing this useless work.