A 3G mobile phone, ______to be most useful and fashionable, is popular with some teenagers.
We have made ________ a rule________ in the office.
With a lot of difficult problems _________, the newly-elected president is having a hard time.
I still remember _______ to the Tian’anmen Square and what I saw there.
More highways have been built in China,________ it much easier for people to travel from one place to another.
I was in the middle of my call because I had no more coins to put in the box.