It is acknowledged that ________ shortest distance between persons is ________ sincere smile.
| A．a；the | B．the；a |
| C．a；/ | D．the；/ |
_______ in the 1800s and first mass-produced in Germany, the harmonica(口琴) was designed to play simple folk tunes.
| A．Being invented | B．Inventing | C．Invented | D．Having invented |
The old scientist has been invited to a party ________ next Monday evening.
| A．holding | B．hold | C．being held | D．to be held |
As soon as she entered the room, the girl caught sight of the flowers ________ by her mother.
| A．buying | B．being bought | C．were bought | D．bought |
________ he had won the first prize, he felt very happy.
| A．Know | B．Known | C．Knowing | D．Being known |
________ their lessons, they went to the cinema.
| A．Finishing | B．Had finished | C．Finished | D．Having finished |