_____a reply he decided to write again.
| A．Not receiving | B．Receiving | C．Not having received | D．Having not received |
154. Using renewable energy is a simple idea, but ______ we find it hard to put into practice.
| A．one | B．what | C．which | D．That |
155. In Beijing volunteers are making use of every minute to ______ their foreign languages because volunteers must pass a written test and an interview.
| A．polish up | B．take up | C．put up | D．make up |
156. As is known to all, hard work will _____ in time.
| A．pay out | B．pay back | C．pay up | D．pay off |
157. The journey that _____ change Toby’s life started in July that year.
| A．would | B．was going to | C．was about to | D．was to |
158. It is said in the book that Thomas Edison _____ the world leading inventor for about sixty years.
| A．would be | B．has been | C．was | D．had been |