Though Jack was poor and sick, he never ______ any chance to write. That is why he finally became a successful writer.
It is _______ unusual thing for us to find ________ UFO.
It takes me two hoursmy homework every day.
I often saw the boysin the river.
This math question is too difficult. Can you help me?
Mr. Black asks the kids ________ in the river, because it’s too dangerous.