Fill in the blanks using Past Perfect Continuous: a) They (wait) for an hour before the bus arrived. b) She (study) all night before the exam. c) I (work) at the company for five years before I decided to leave.

Here are the sentences completed using the Past Perfect Continuous:

1. a) They had been waiting for an hour before the bus arrived.
2. b) She had been studying all night before the exam.
3. c) I had been working at the company for five years before I decided to leave.

Explanation:

The Past Perfect Continuous tense is used to describe an action that had been in progress for a period of time before another action occurred in the past. It is formed using 'had been' + the present participle (verb + -ing).

• a) had been waiting: Shows that the waiting was in progress for an hour before the bus arrived.
• b) had been studying: Shows that she was studying all night before the exam.
• c) had been working: Shows that I was working at the company for five years before I decided to leave.