It is ___world of wonders, world where anything can happen.
____ has helped to protect the environment is worth praising.
—Why didn’t Tom go to the concert last night ? — I have no idea, but I think he _____ in his study.
Being examined twice a year is the rule that every driver _____ obey in this city.
I’m calling to ask for information about the position____ in the local TV news.
It has been proved ____ several new kinds of medicine____ a positive effect on the cure of H7N9.