.Our teacher is very busy.He is ________ in working out a teaching plan.
Mrs.Smith finds it hard to clear up the mess,as her children are always ________ whenever she tries to.
Before you pay a visit to a place of interest, look in your local library________a book about it.
Everything comes with ________ price;there is no such ________ thing as a free lunch in the world.
Many people agree that ________ knowledge of English is a must in ________ international trade today.
In the market,vegetables are sold by ________ kilogram,I mean,by ________ weight.