. Look! There is a whole crowd of people over there. Go and see what_____ and if it is a bargain, buy it. A is selling B is being sold C has been selling D has been sold
An engineer has designed _______ robot that can work in _______ deep sea to clean waste.
—What do you think I should wear for such a formal press conference? —Dress _______ you like.
Radium salts,which have been found to ______ in bones,give rise to bone cancer.
Our teacher insisted that the key words worth paying attention _______ before class.
With some technical problems to be solved, it may be a while _______ the system is put into use.