26.IfI ______________the challenges at that time, I might not have started my own business.

A)would know
B) have known
C)had known
D) will know

27. It was not until last July___________we started to distribute e-readers and launched ane-book store.

A)that
B)who
C)which
D)whom

28.__________the library for hours without finding anything useful, I turned to my professor for help.

A)To search
B)Having searched
C)Have searched
D)Searching

29.___________some degree,all managers who supervise peoplc are involved in HR activities.

A)On
B)To
C)For
D)With

30. Our online computer repair and tech support is a convenient way to have your computer___________withouthaving to leave your home.

A)to fix
B)fixing
C)fix
D)fixed

Section B31. This chapter will assist you in preparing and writing memos that allow you to communicate (effective)_____________in today's workplace.

32. Thank you for your email, and your feedback on the (attach)______________proposal would be appreciated.

33. There is no (different)_____________in the brains of those who exercise with light intensity as comparedwith those who do not exercise at all.

34.When they entered the area,the visitors (require)___________to turn off their smartphones.

35. When it comes to shopping habits, he suggested (buy)__________products that arc made from recycledmaterials.