单选题 The research is intended to ____ the relationship between the economy and education.

单选题 There was widespread concern in the U.S. that the rising unemployment might ____ a threat to social stability.

单选题 It was about 30 seconds before Alex ____ from the water; we were quite scared.

单选题 It is well - known that China is a country with rich natural ____ and a very long history.

单选题 After a(n) ____ physical exam, my doctor said I was in good health except that my blood pressure was a little high.

单选题 They are planning to spend the money on something that will be of great ____ to everyone in the community.

单选题 Some people believe that the earth can ____ enough food to support at least twice its present population.

单选题 There is no room for more furniture in our apartment - we've used up all the space ____.