1. Underline the correct form. 1 They have talked/have been talking about it all morning. 2 He's not here because he has been going/has gone to work. He'll be back at 4 o'clock. 3 The children cleaned/have been cleaning the playground yesterday. 4 She has studied/has been studying all day. 5 I worked/have been working without a break since 8 o'clock. 6 I have been walking/walked to the park last week.

Grammar Explanation: Present Perfect vs. Present Perfect Continuous

• Present Perfect (have/has + past participle) is used for completed actions in the past, especially when the result is important, or when the duration is not specified or important.
• Present Perfect Continuous (have/has been + -ing) is used for actions that started in the past and are still continuing in the present, or have just finished, with an emphasis on the duration or the activity itself.

Answers:

• 1. They have been talking about it all morning. (Emphasis on the ongoing action of talking throughout the morning.)
• 2. He's not here because he has gone to work. He'll be back at 4 o'clock. (Action of going to work is completed, and the result is his absence.)
• 3. The children cleaned the playground yesterday. (Completed action at a specific time in the past.)
• 4. She has been studying all day. (Emphasis on the continuous activity of studying throughout the day.)
• 5. I have been working without a break since 8 o'clock. (Emphasis on the duration of the continuous activity.)
• 6. I have been walking to the park last week. (Emphasis on the continuous action of walking, or a recently completed action with ongoing relevance. If it were a one-time event, 'walked' might be used, but 'have been walking' suggests a recent habit or ongoing process.)