—Xiaoming, you are late again, can you tell me why?—I was on the half way when it _______to me that I had left my notebook at home, so I have to fetch it.

You are working too hard.You’d better keep a________between work and relaxation.(2012·天津，3)

Once we discover a mistake, we should not _____ it but correct it immediately, to create better conditions for economic development.

Most students think this book is useful as it ____ all the basic grammar rules they        need to know.  

Living with a host family while studying abroad, in which there may be some other college students, __________ you the chance to learn more about the new culture.