In order to attract more customers,many supermarkets usually sell their goods at a good     at weekends.

His new appointment takes _____ from the beginning of next month.

There are _____advertisements which encourage ______to participate in improving their neighbourhood.

Shelly had prepared carefully for her biology examination so that she could be sure of passing it on her first ______.

In the meantime, the question facing business is whether such research is ______ the costs.