It’s the gases ___ natural gas and the burning of coal give off ____ add to the overheating of the earth.

It is in the hotel _____ he stayed last night ______ he lot his mobile phone.

It was ______ back home after the experiment.

Personally, I think it’s your attitude, rather than your score, ______ matters in your study.

It was when she was sleeping in her bedroom __________ a thief broke into the house.

It is not how much we learn but how much we understand ______ benefits us so much in our daily life.

– Do you know _____ yesterday ?
– It was at 8 o’clock in the morning.

—______ that he managed to get the book?
— Oh, his sister helped him.

It was not until mid-night _____ he went back home after the experiment.

---He was nearly killed by a car once.
---Oh, when was _____ exactly?
---It was in 2007 _____ he was riding a bike on the drive-way.