Returning from abroad, Miss Yu received from her lovely students a nice present to which a note was ______, saying “We love you!”
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.