If you don’t understand something, you may research, study

28. If you don’t understand something, you may research, study, and talk to other people _______ you figure it out.(C)

A. because B. though C. until D. since

29. In the 1950s in the USA, most families had just one phone at home, and wireless phones _______ yet. (D)

A. haven’t invented B. haven’t been invented

C. hadn’t invented D. hadn’t been invented

30. The national park has a large collection of wildlife, _________ from butterflies to elephants. (A)

A. ranging B. range C. to range D. ranged

31. The little problems ______ we meet in our daily lives may be inspirations for great inventions.(A)

A. that B. as C. where D. when

32.Jim has retired, but he still remember the happy time _______ with his students.(D)

A. to spend B. spend C. spending D. spent

以上为北京高考英语试卷的部分试题及答案，仅供参考。