It was not until this year _____ scientists managed to make a cat and a goldfish disappear from sight using an invisibility cloak(斗篷)
After the teacher called him into the office, the boy admitted _______ in the test.
It was in Beihai Park _____ they made a date for the first time ______ the old couple told us their love story.
.Only when your identity has been checked ________.
More and more people are beginning to _____ importance to living a low-carbon(低炭) life.
The number of people visiting the exhibition ______ 50, and a number of them ____ painters.