The two girls are so alike that strangers find ________ difficult to tell one from the other.
I wish to thank Professor Smith, without ______ help I would never have got this far.
—Amy, please tell the people ______ for their turns to come to my office five minutes later. — Yes, sir.
The organizers promised ______ won the first prize would have a chance to go abroad.
Three suspects ________ in the terrorist attack inKunminghave been caught.
According to the new law, people found putting up “harmful” ads on the streets _______be punished.