Many firms give away small quantities of their productions as _______ so that people can try them before buying.
If you make most of every minute in class day after day, there will be switch in grades.
My English teacher gave us a suggestion yesterday, _____is often the case, ______ our monitor organize a debate after class.
Tsinghua University, ______ in 1911, is home a great number of outstanding figures.
It was three months later _____ he completed the job with difficulty.
He is rather difficult to make friends with, but his friendship, _____ is more true than anyone else’s.