The scientists recommend that studies ________ to find out what side effects the medicine might cause.
–I’m sorry. I _______ at you the other day. --Forget it. I was a bit of out of control myself.
Which of these paintings was painted by the famous artist Leonardo da Vinci? _______.
To turn off my cell phone before going to bed seems to be a rule .
—Did you have any trouble in getting here ? — No . I would have telephoned you .
There were so many cars held up by the heavy rain on the road that we had no but to wait.