All the students are talking and laughing in the classroom and it’s______ .

Will you buy this nice camera, Henry?– No. It’s too expensive. I can’t ________ it.

Please listen to the teacher as _______ as you can in class.

Yesterday the teacher told us that the earth ________around the sun.

Do you know ____________ the population of China is?—Yes, it has the __________ population in the world, about 1.3 billion.