There was a big forest fire last week, but nobody knows how it .
Research _______ that over 90 percent of high school students are dissatisfied with their test scores.
His face an embarrassed smile when he heard the result of the competition.
When the disabled sportsman won a gold medal,a lot of people him on his Success.
— Sunny day, isn't it? — Let's hope the sunny weather for Saturday's tennis match.
This problem may lead to more serious ones if___ unsolved.