_______ on time, this medicine will be quite effective.
| A．Taking | B．Being taken |
| C．Taken | D．Having taken |
Everyone has periods in their lives ______ everything seems very hard.
| A．when | B．where | C．which | D．that |
By the time we reach that page, we ___________ twenty lessons of the book.
| A．will study | B．will have studied | C．would study | D．have studied |
On hearing the bad news, he got up quickly ______ the lunch unfinished.
| A．leaving | B．left | C．to leave | D．leave |
The girl looked at me with a _______expression. Maybe the problem was quite ______.
| A．puzzled; puzzling | B．puzzling; puzzled |
| C．puzzled; puzzled | D．puzzling; puzzling |
Would you please ______ your statement again? I don’t understand what you were saying.
| A．classify | B．clear | C．clarify | D．charity |