<p><span>1. Nobody has seen him </span><strong><span class="CorrectAnswer">since</span></strong><span> last Friday.</span><br /><br /><span>2. It has been foggy </span><strong><span class="CorrectAnswer">for</span></strong><span> some days.</span><br /><br /><span>3. He has been fishing </span><strong><span class="CorrectAnswer">since</span></strong><span> six o'clock.</span><br /><br /><span>4. They've been living in France </span><strong><span class="CorrectAnswer">for</span></strong><span> eight years.</span><br /><br /><span>5. The pilots have been on strike </span><strong><span class="CorrectAnswer">for</span></strong><span> two months.</span><br /><br /><span>6. We've had terrible weather </span><strong><span class="CorrectAnswer">since</span></strong><span> Saturday.</span><br /><br /><span>7. I've known Tom </span><strong><span class="CorrectAnswer">since</span></strong><span> 1990.</span><br /><br /><span>8. We have been waiting for the bus </span><strong><span class="CorrectAnswer">for</span></strong><span> half an hour.</span><br /><br /><span>9. She hasn't lost a match </span><strong><span class="CorrectAnswer">since</span></strong><span> April.</span><br /><br /><span>10. Things have changed </span><strong><span class="CorrectAnswer">since</span></strong><span> she's become headmaster.</span><br /><br /><span>11. The police have been looking for him </span><strong><span class="CorrectAnswer">for</span></strong><span> a month.</span><br /><br /><span>12. Our dog has been ill </span><strong><span class="CorrectAnswer">for</span></strong><span> two days.</span><br /><br /><span>13. I've been looking for this book </span><strong><span class="CorrectAnswer">for</span></strong><span> a long time.</span><br /><br /><span>14. I've been working </span><strong><span class="CorrectAnswer">since</span></strong><span> I got up.</span><br /><br /><span>15. The kettle has been boiling </span><strong><span class="CorrectAnswer">for</span></strong><span> ten minutes.</span></p>