19. His first book next month is based on a true story.
| A．published | B．to be published | C．to publish | D．being published |
________ his lessons , he failed in the exam.
| A．Not reviewing | B．Having not reviewed | C．Not reviewed | D．Not having reviewed |
Maybe you have been to many countries, but nowhere else _______ a more beautiful palace.
| A．can you find | B．you could find | C．you can find | D．could you find |
This problem may lead to more serious ones if_______ unsolved.
| A．making | B．left | C．remained | D．keeping |
________, you need to give all you have and try your best.
| A．Being a winner | B．To be a winner |
| C．Be a winner | D．Having been a winner |
Many human activities also _______carbon gases, which will result in global warming.
| A．put off | B．send off | C．let off | D．set off |