Emergency line operators _______ always stay calm and make sure that they get all the information they need to send help.
| A．can | B．would | C．must | D．might |
Coming into the room, I found them ______ at the table, _____ chess.
| A．seated; playing | B．seating; playing | C．seat; play | D．seated; played |
If you ______ go, at least wait until the rain stops.
| A．can | B．must | C．should | D．would |
I ______ her, but I never could.
| A．ought to help | B．must help | C．must have helped | D．ought to have helped |
— Anything new in the new regulations（规则）? — They will ______ to us all.
| A．great benefit | B．do harms | C．do good | D．for the benefit |
We don’t doubt _____ he will succeed in the research work.
| A．that | B．whether | C．how | D．what |