【单选题】Over the past two decades, teenage childbearing in the United States experienced a downward trend, and births to unmarried teens between 1970 and 1990______.
【简答题】用括号中所给词的适当形式填空。 1. ______ (age) want to go to the Watertown. 2. He got two ______ (Australia) stamps from his friend. 3. The Yellow River is the ______ (two) longest river in China. 4. Alice asks ...