**Rule**: **Subject-Verb Agreement**. A collective noun like 'jury' is treated as a singular unit when it acts together with one voice. It takes a plural verb (e.g., 'are') only when the individual members are being referred to. Here, the jury as a single entity is unable to decide. **Correct Usage**: The singular verb 'is' correctly treats the jury as a single, cohesive unit. **Incorrect Options**: (a) 'are' and (c) 'have been' would be used if the members were acting individually (e.g., 'The jury are arguing among themselves'). (d) 'has' is an incomplete verb form here.

**Rule**: The **Present Continuous Tense** is used to describe a temporary action or weather condition that is happening now or today. **Correct Usage**: 'is shining' correctly describes the weather on this specific day ('today'). **Incorrect Options**: (a) 'shines' (Simple Present) is a general truth. (c) 'has shone' (Present Perfect) refers to the shining that has happened up to this point. (d) 'shine' is a plural verb.

**Rule**: **Subject-Verb Agreement**. When a collective noun like 'pack' is used to refer to the group as a single unit, it takes a singular verb. The **Simple Present Tense** is used for a permanent or long-term situation. **Correct Usage**: 'lives' is the correct singular verb for the singular subject 'A pack'. **Incorrect Options**: (a) 'live' is a plural verb. (b) 'is living' (Present Continuous) might suggest a temporary situation. (d) 'has lived' (Present Perfect) is the wrong tense for a statement of current, ongoing fact.

**Rule**: The **Present Continuous Tense** is used to ask about an action that seems to be in progress now, often based on present evidence ('I can smell something burning'). **Correct Usage**: 'Are you cooking' is the correct question form to ask about the ongoing action that is causing the smell. **Incorrect Options**: (a) 'Do, cook' (Simple Present) asks about a habit. (b) 'Have, cooked' (Present Perfect) asks about a completed action. (d) 'Did, cook' (Simple Past) asks about the past.

**Rule**: The **Present Perfect Continuous Tense** is used for an action that has been in progress for a duration of time ('for two hours') and has a present sensory result ('it smells wonderful'). **Correct Usage**: 'has been simmering' correctly links the long, continuous cooking process to the current aroma. **Incorrect Options**: (a) 'simmers' (Simple Present) is for instructions. (b) 'is simmering' (Present Continuous) is for now. (d) 'has simmered' (Present Perfect) focuses on completion.

**Rule**: **Stative Verbs**. Verbs related to senses, emotions, and states (like 'taste', 'smell', 'feel', 'seem', 'love') are generally not used in the continuous form. They are used in the **Simple Present Tense** to describe a current state. **Correct Usage**: 'tastes' describes the current quality of the soup. As 'soup' is a singular subject, the verb takes an '-s'. **Incorrect Options**: (a) 'is tasting' is incorrect because 'taste' is a stative verb in this context. (c) 'has tasted' is the wrong tense. (d) 'taste' is for plural subjects.

**Rule**: The **Present Perfect Continuous Tense** is used to describe an activity that started in the past, has continued for a duration ('for five years'), and has a present result ('is very successful'). **Correct Usage**: 'has been running' emphasizes the continuous effort and management of the business over the five-year period leading to his current success. **Incorrect Options**: (a) 'runs' (Simple Present) states it as a fact. (b) 'is running' (Present Continuous) is for now. (d) 'has run' (Present Perfect) is also possible but focuses less on the continuous effort.

**Rule**: The **Present Perfect Continuous Tense** is used to emphasize the duration ('all week') of an action that started in the past and is still ongoing. **Correct Usage**: 'have been waiting' perfectly describes the long, continuous period of anticipation for the package. **Incorrect Options**: (a) 'wait' (Simple Present) is a habit. (b) 'am waiting' (Present Continuous) is for now. (d) 'waited' (Simple Past) is a completed action.

**Rule**: This sentence combines a **Simple Present** state with a **Present Perfect Continuous** action that explains it. **Correct Usage**: 'He **is** an expert' describes his current state (Simple Present). The reason for this state is that 'he **has been studying** the subject for over 20 years', showing the long, continuous action leading to his present status (Present Perfect Continuous). **Incorrect Options**: The other combinations create a mismatch in tenses. (a) 'is, studies' uses the wrong tense for the durational action. (c) 'has been, studies' incorrectly uses present perfect for the state. (d) 'was, studied' puts both clauses in the past.

**Rule**: The **Present Perfect Continuous Tense** is used for a habitual action that started at a specific point in the past ('since it first aired') and has continued regularly up to the present. **Correct Usage**: 'have been watching' correctly emphasizes the long, continuous viewership of the show. **Incorrect Options**: (a) 'watch' (Simple Present) is a habit without the historical context. (b) 'am watching' (Present Continuous) is for now. (d) 'watched' (Simple Past) is a completed action.