．The theory is true _______ the hotter a body is, the more energy it gives off.

In the US, students can do almost anything they want in class, ____ they don’t make too much noise or disturb others who want to learn from the teacher. 

—You look tired, Jack． What's wrong with you?—Oh, 1 worked quite late last night． Nothing wrong with me,       ．

______ you have finished your work, you ought to have a good rest. 

Try to read stories in English and speak in English whenever you can，________ you will see more progress over time.