Over the past decades, sea ice _______ in the Arctic as a result of global warming.
| A．had decreased | B．decreased |
| C．has been decreasing | D．is decreasing |
So far nobody has claimed the money in the library.
| A．discovered | B．to be discovered | C．discovering | D．having discovered |
Dina,for months to find a job as a waitress, finally took a position at a local advertising agency.
| A．struggling | B．struggled | C．having struggled | D．to struggle |
Listen! Do you hear someone for help?
| A．calling | B．call | C．to call | D．called |
He had a wonderful childhood, _____with his mother to all corners of the world
| A．travel | B．to travel | C．traveled | D．traveling |
Thai is the only way we can imagine the overuse of water in students' bathrooms.
| A．reducing | B．to reduce | C．reduced | D．reduce |