--How soon will Henry be back?—He said he would come home ___ four o’clock.
In the 21st century, all nations must take their ________of responsibility for the global safety.
-----How good the news is for you!------ ______________.
What worried the mother most was __________ the Internet after class in this school.
------- Jack, you erase the blackboard today, __________?------- But I did it yesterday.
To me, cycling at ___ altitude of more than 4,000 meters was _____ unforgettable experience.