**Rule**: The **Present Perfect Tense** in the negative with 'yet' is used to show that an expected action has not happened up to the present moment. **Correct Usage**: 'hasn't given' correctly states that he has not expressed his opinion in the time leading up to now. **Incorrect Options**: (a) 'doesn't give' (Simple Present) is a habit. (b) 'isn't giving' (Present Continuous) is for now. (d) 'didn't give' (Simple Past) requires a specific past time frame.

**Rule**: While 'hope' is a stative verb, the **Present Perfect Continuous Tense** ('have been hoping') is sometimes used informally to emphasize the continuous, ongoing nature of a desire over a period of time ('all week'). **Correct Usage**: 'have been hoping' stresses the continuous and perhaps frustrating state of hope over the past week. 'have hoped' would be the more grammatically standard choice. **Incorrect Options**: (a) 'hope' (Simple Present) is for the present. (b) 'are hoping' is also possible but less connected to the duration. (d) 'hopes' is a singular verb.

**Rule**: The **Simple Present Tense** is used to state general truths or scientific facts. **Correct Usage**: The fact that water boils at 100 degrees Celsius is a universal truth. The subject 'Water' is a third-person singular (uncountable) noun, so the verb takes an '-s'. Thus, 'boils' is correct. **Incorrect Options**: (a) 'is boiling' (Present Continuous) would mean the water is boiling right now. (c) 'has boiled' (Present Perfect) implies a recently completed action. (d) 'boil' is used with plural subjects.

**Rule**: The **Present Continuous Tense** can be used to talk about current analyses or predictions that are being made. **Correct Usage**: 'are predicting' suggests this is the current consensus or ongoing discussion among economists. The subject 'The economists' is plural. Simple Present ('predict') is also possible to state their conclusion as a fact. **Incorrect Options**: (a) 'predict' is also a valid option. (c) 'have predicted' (Present Perfect) announces the prediction as recent news. (d) 'predicts' is a singular verb.

**Rule**: The **Present Perfect Tense** is used with stative verbs (like live, know, be) to describe a state that started in the past and continues to the present, especially with 'for' and 'since'. The Present Perfect Continuous ('have been living') is also possible and emphasizes the continuous nature. **Correct Usage**: 'have lived' is correct because the action of living started in the past (1995) and continues now. The subject 'My parents' is plural. **Incorrect Options**: (a) 'live' (Simple Present) doesn't convey the duration from the past. (b) 'are living' (Present Continuous) is usually for temporary situations. (c) 'has lived' is for singular subjects.

**Rule**: The **Present Perfect Continuous Tense** is used to talk about a difficult situation that has been ongoing for some time and is still relevant or just ending. **Correct Usage**: 'has been facing' correctly describes the prolonged struggle that is now beginning to change. **Incorrect Options**: (a) 'faces' (Simple Present) is a general statement. (b) 'is facing' (Present Continuous) focuses only on the present struggle. (d) 'face' is a plural verb.

**Rule**: The **Simple Present Tense** is used to describe a general truth or a characteristic of a type of person. **Correct Usage**: 'sees' correctly describes the habitual tendency of an optimist. The subject 'An optimist' is singular. **Incorrect Options**: (a) 'is seeing' is incorrect as 'see' (meaning 'perceive') is stative. (b) 'has seen' (Present Perfect) is for past experiences. (d) 'see' is a plural verb.

**Rule**: The **Simple Present Tense** is used for future events that are part of a fixed schedule or timetable. **Correct Usage**: A lecture's start time is a scheduled event. Therefore, 'starts' is the correct verb for the singular subject 'The lecture'. **Incorrect Options**: (b) 'is starting' (Present Continuous) can be used for future plans but simple present is more common for official schedules. (c) 'has started' (Present Perfect) is incorrect as the event is in the future. (d) 'start' is for plural subjects.

**Rule**: **Stative Verbs**. 'Belong' is a stative verb of possession and is not used in continuous tenses. The **Simple Present** is used to state a fact of ownership. **Correct Usage**: 'belongs' correctly states the fact of who owns the car. The subject 'That old car' is singular. **Incorrect Options**: (a) 'is belonging' is grammatically incorrect. (b) 'has belonged' would be used with 'for' or 'since'. (d) 'belong' is a plural verb.

**Rule**: The **Present Perfect Tense** is often used to announce recent actions or decisions, especially by governments or organizations. **Correct Usage**: 'has introduced' correctly reports the recent action, implying that the regulations are now in effect or about to be. **Incorrect Options**: (a) 'introduces' (Simple Present) is a habit. (b) 'is introducing' (Present Continuous) can be used for a future plan, but present perfect is better for announcing a completed action. (d) 'introduce' is a plural verb.