42. D。从they are hungry creatures, not content with only three meals a day可知答案。

41. C。文章第三节。

40. C。文章第一节中：We owe a lot to the birds and beast who eat insects, but all of them put together kill only a very small amount of the number destroyed by spiders.

39. B。第三节中可推出答案。

38. D。第四节第五行some students think it will affect their freedom and privacy可知答案。

37. D。文章第二节最后一句。

36. D。从文章第二节第四行和地五行可知。

34. A。谓语动词pause后，examine又是动词原形，所以这里应当选to，可构成动词不定式，做目的状语。其余选项都是介词，不合题意。

33. B。固定短语to begin with，意为“首先，第一”，常用做插入语。