He failed the final examination and only then ____ how much time he had wasted.
| A．he realized | B．had he realized |
| C．he had realized | D．did he realize |
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 |
159. The wages ______ him will be paid tomorrow.
| A．due to | B．because of | C．thanks to | D．according to |
160. I don’t really work here; I ______ until the new secretary arrives.
| A．just help out | B．have just helped out |
| C．am just helping out | D．will just help out |
161. As I was about to speak ______ you interrupted me.
| A．/ | B．when | C．as | D．but |
162. Many countries are increasing their use of natural gas, wind and other forms of ______.
| A．energy | B．source | C．power | D．Material |