As can be gathered from the passage, before 1910 the normal running time of a film was probably ______.

单项选择题Griffith's film innovations had a direct effect on all of the following EXCEPT ______.

单项选择题Which of the following is the author implying in paragraph 5

单项选择题The author's intention is to get us to ______.

单项选择题How would you describe the author's attitude towards current learning strategies

单项选择题What does the author mean by the word progress in this passage