All over the city, history and modernity come together to make _______ an essential place for tourists to discover.
| A．each | B．this | C．one | D．it |
_________ a certain doubt among the people as to the practical value of the project．
| A．It has | B．It remains | C．They have | D．There remains |
The hours ________ the children spend in their one way relationship with television people undoubtedly affect their relationships with real-life people．
| A．that | B．when | C．in which | D．on which |
Low-carbon lifestyle is of great benefit to improve the world environment, but the problem is difficult to _________．
| A．solve | B．be solved | C．solve with | D．solving |
After ten years abroad, he still recognized his old colleagues ________ he set foot in China．
| A．immediately | B．for the first time |
| C．while | D．moment |
We won’t forget the financial crisis and the troubles _______ has caused to the people all over the world．
| A．which | B．this | C．what | D．it |