29. Do what you think is right, ____ they say.

( )51. The other wonders of the ancient world were destroyed by earthquakes, fire or other reasons except the Pyramids of Giza.

21. Trapped in the forest, the travelers have had ____ biscuits for 5 days.

47. An active volunteer helps others usually ______. 

24. He ought to have come by now. I ____ that some accident has delayed him.

31. The engineers are going through with their highway project, ____ the expenses have risen.

61. 让我们利用这次长假去香港旅游。

59. 与不同经历的人相处会有助于开阔你的视野。

32. Stressful environment leads to unhealthy behaviors such as poor eating habits, which ____ increase the risk of heart disease.

56. 骑自行车是一种很好的锻炼方式，并且还容易学。

39. What online language programs have been introduced to attract the Internet users and help users make progress?

60. 林肯之所以如此受尊敬是因为他也同样不是完人。