Carbon dioxide, which makes a ______ between us and the sun, prevents heat from getting out of the atmosphere easily, so the earth is becoming warmer.

The room became ______ crowded after the desk was moved out. 

—Don’t be so naughty! Be your ________.—Got it，mum. 

Natural learning environments inspire a burning ________ to learn, the key to a productive lifestyle.

Transit, a car made in Jiangxi province, was sold nearly 50,000 units in 2012, with the total value_____ it was in 2008．