**Rule:** 'Be going to' is used to express a future plan or intention that has already been decided. The phrase 'I've decided' clearly indicates a prior intention. Option (a) 'will use' is for a decision made at the moment of speaking, which contradicts 'I've decided'. Options (c) and (d) are incorrect.

**Rule:** The 'be going to' form is used to talk about a prior plan or intention. The phrase 'I've decided' clearly indicates that the decision was made before the moment of speaking. Option (a) 'will buy' is used for spontaneous decisions, which contradicts 'I've decided'. Options (b) and (d) are incorrect in this context of expressing a prior intention.

**Rule:** The Future Perfect Tense (will have + past participle) is used to express that an action will be completed by a specific future deadline. 'By the end of the day' is the deadline by which the action of interviewing all candidates will be finished. Option (c) implies the action will be in progress at that time.

**Rule:** The Simple Present Tense is used for future events that are part of a fixed schedule or program. The end of a conference is a scheduled event. Therefore, 'concludes' is the most appropriate and formal choice. Options (a) and (d) are also possible for planned events, but simple present is standard for schedules.

**Rule:** The Simple Future Tense ('will' + base verb) is often used to state a future fact or something the speaker believes is certain to happen. In this context, the speaker is confidently stating a future event. While (c) is also possible, (d) is a very common and natural way to express this. Option (a) is simple present. Option (b) is for fixed arrangements, which might not be the case here.

**Rule:** The Present Continuous Tense ('Are you planning') is used here to ask about someone's current plans or arrangements for the future. It's a way of confirming a plan that the speaker has just heard about. 'Are you going to move' would also be correct. Option (a) is a less personal question about a prediction.

**Rule:** 'Be going to' is used for predictions based on present evidence or trends. 'The current rate of progress' is the evidence that leads to the logical conclusion that the goals will not be met. Option (b) is a simple prediction, but (d) is stronger as it is based on the current situation.

**Rule:** The Future Perfect Tense (will have + past participle) is used to express an action that will be completed by a certain time in the future. The deadline 'By 2030' indicates that the action of finding a cure will be finished before or at that point. Option (a) 'are finding' is Present Continuous. Option (b) 'will be finding' (Future Continuous) suggests the action will be ongoing in 2030, not completed. Option (d) 'found' is Simple Past.

**Rule:** The Future Perfect Tense (will have + past participle) is used to indicate that an action will be completed by a specific future deadline. 'By the end of the day' is the deadline by which the planting will be finished. Option (c) means the action will be in progress at the end of the day, not completed.

**Rule:** The Simple Future with 'will' can be used to state an intention that is a logical consequence of a situation. Because the event is formal, the speaker states their resulting intention to wear a suit. 'am going to wear' would also be correct, but 'will' is a natural choice for expressing this kind of consequential decision. 'am wearing' (option c) implies a fixed arrangement.