The word "underscore" in the last sentence of the text probably means"______".

单项选择题The 2003 survey reveals that ______.

单项选择题Which of the following elements is the most critical to online security according to the author

单项选择题Which of the following statements does the author imply

单项选择题An operating system is no guarantee of online security probably because ______.

单项选择题The best title for the passage would be ______.

单项选择题To define science we may simply call it ______.

单项选择题Pure science, leading to the construction of a microscope, ______.

单项选择题According to the passage, the use of Antarctic krill as a food is an innovation whose future is ______.

单项选择题A scientist being interested in adding to our general knowledge about oxygen would probably call his approach ______.

单项选择题The cultural communication problems are becoming especially urgent for ______.