The research is so designed that once _____ nothing can be done to change it.
John brought over my letter _______ to him by mistake.
_______ here if you want to get a better view of the mountain scenery.
--- Can I help you? --- Yes. I bought an iPhone 6 here last week, but there _______ something wrong with it.
He promised that he ______ us in the party, but he hasn’t turned up until now.
There are about one million words in English. ________, most people use only about ten thousand of them.