It seems that living green is ________easy and affordable. A small step makes a big difference.
No one can be sure in a million years.
____ students are practicing ___ English with each other at the English corner.
My father served in the army in _______ when he was in _____.
Only when finished his own work, ask him to help you.
The reason he missed this class was quite different from the one that you explained to me. A.that B.of which C.why D what