单项选择题 The ______ of gifted children into accelerated classes will start next week according to their academic performance.

单项选择题 Her sadness was obvious, but she believed that her feeling of depression was ______.

单项选择题 Now the public has an unprecedented chance to peer over the shoulders of archaeologists and historians and get a firsthand look at the ______ of the Mongols and their Asian predecessors.