阅读下面短文，从每题所给的A、B、C、D四个选项中选出最佳选项。 Teachers say the digital age has had a good and a not-so-good influence on the American teenagers. More than 2,000 high school teachers took an online survey. 75 percent of the teachers said the Internet and digital search tools have had a “mostly good” use for their students' research habits and skills. But 87 percent agreed that these technologies “make the students not have enough attention.” And 64 percent said the technologies “do little to help them in courses.” Judy Buchanan is a director of the National Writing Project. Ms. Buchanan says digital research tools are helping students learn more, and learn faster. Teachers really like these tools, because there are ways to make some of learning exciting. Young people enjoy using these tools. And the goal is to help them become creative students of meaningful work, and not just that kind of copyist. But one problem the survey found is that many students don't have a good understanding of how to use the digital knowledge well. In other words, they trust(信任) too much of the information. Judy Buchanan says these students, have not developed the skills they need to tell whether the online information is good or bad. Another problem the survey found is something that might not seem like a problem, at all, being able to quickly find information online. Teachers say the ability of their students to work hard to find answers is becoming weaker. They say students depend too much on search engines(引擎) and do not make enough use, of printed books or research librarians. Besides, many teachers are also worried about the problem that the Internet makes it easy for students to copy work done by others instead of using their own abilities.________ of the teachers agreed technologies may stop students from having enough attention.
How many problems are mentioned(提及) in the passage?
Teachers like the digital search tools because they can ________.
What does the writer want to tell us by writing this passage?