_______ the calculation is right, scientists can never be sure that they have included all variables and modeled them accurately.
-----Tom passed the final exam . ---______, and _______.
He had decided to give it up, but on ______ second thought, he decided to try ____ 3rd time.
What does it ________ if I spend $ 100 on it ---it’s my money.
More and more people choose to shop in a supermarket as it offers a great _____ of goods.
Mr. Wang has been selected_________ chairman of the conference.