A. to leave B. leaving C. to have left D. leftYou shoul……

单项选择题—I'm going to study engineering in Tsinghua University tomorrow. —______.

单项选择题Bats are surprisingly long-lived creatures, some ______ a life span of around 20 years.

单项选择题是英语学习成功的关键。

单项选择题直接法强调______的重要性。

单项选择题捷克教育家夸美纽斯说过：“教师的嘴是一个源泉，从那里可以产生知识的溪流。”这指的是教师的( )。