**Rule:** The Future Continuous Tense (will be + verb-ing) is used to describe an action that will be in progress at a specific time in the future. 'This time tomorrow' pinpoints the future moment when the action of flying will be ongoing. Option (d) implies the flight is already finished.

**Rule:** The Future Perfect Tense (will have + past participle) is used to express that an action will be completed by a certain future time. The deadline is 'by the end of the week', and the action of replacing all the windows will be finished by then. Option (d) implies the work will be ongoing at that time.

**Rule:** The Simple Future with 'will' is often used to give reassurance or make a confident prediction. The speaker is reassuring someone about a future event. While (d) is also for predictions, 'will' is very common in phrases of reassurance like 'Don't worry'. Options (a) and (c) are incorrect.

**Rule:** The Simple Future with 'will' (or 'will not') is often used to express a strong resolution or decision made at the moment of speaking. The speaker's shock ('I can't believe he said that!') leads to the immediate, firm decision not to speak to him again. Option (c) implies a prior decision, which is less fitting for a spontaneous reaction.

**Rule:** The Future Perfect Tense (will have + past participle) is used to describe an action that will be completed by a future deadline. The verb 'hopes' is followed by a clause describing the desired future outcome, which is the completion of the action ('reaching the target') by the deadline ('by the end of the quarter').

**Rule**: The **Past Perfect Tense** is used with 'by' + a past time reference to talk about achievements completed before that point. **Correct Usage**: Starting the company ('had started') and becoming a millionaire were achievements completed before his 40th birthday. **Incorrect Options**: (a) 'started' (Simple Past) is less precise. (c) 'was starting' is an ongoing process. (d) 'starts' is a present tense.

**Rule**: The **Simple Past Tense** is used for a specific, completed historical event. **Correct Usage**: 'in 1906' specifies a definite past time, so the Simple Past 'suffered' is correct. **Incorrect Options**: (b) 'was suffering' refers to the ongoing event. (c) 'had suffered' would need a later past reference. (d) 'has suffered' is a present tense.

**Rule**: The **Past Continuous Tense** is used for an ongoing mental or physical state that prevented another action from being noticed or completed. **Correct Usage**: She 'was thinking' about something else (the ongoing mental state), and this is the reason she 'didn't hear' the question. **Incorrect Options**: (a) 'thought' (Simple Past) is a completed thought. (b) 'had thought' would mean the thought was over before the question. (d) 'thinks' is a present tense.

**Rule**: The **Past Continuous Tense** is used for a longer, ongoing action that was interrupted by a shorter one. **Correct Usage**: The ongoing activity was 'was watching', which was interrupted by the guests' arrival ('arrived'). **Incorrect Options**: (a) 'watched' (Simple Past) suggests they finished. (b) 'had watched' means the show was already over. (d) 'had been watching' would emphasize the duration before the arrival.

**Rule**: The **Past Continuous Tense** (was/were + verb-ing) describes an ongoing action that was interrupted by another past action. **Correct Usage**: The students' conversation ('were talking') was the longer, ongoing action that was interrupted by the teacher's arrival ('walked in'). **Incorrect Options**: (a) 'talked' (Simple Past) suggests the talking finished before the teacher arrived. (b) 'had talked' (Past Perfect) means their conversation was already over. (d) 'had been talking' (Past Perfect Continuous) would emphasize the duration of their talk before the interruption.