下面的短文后有2项测试任务：
(1)第23-26题要求从所给的6个选项中为第2-5段每段选择1个最佳标题；
(2)第27-30题要求从所给的6 个选项中为每个句子确定1个最佳选项。
Face Masks may not Protect from Super-flu
1 If a super-flu strikes, face masks may not protect you. Whether widespread use of masks will help, or harm, during the next worldwide flu outbreak is a question that researchers are studying furiously. No results have come from their mask research yet.
2 However, the government says people should consider wearing them in certain situations anyway, just in case. But it’s a question the public keeps asking while the government is making preparations for the next flu pandemic. So the Centers for Disease Control and Prevention (CDC) came up with preliminary guidelines. "We don’t want people wearing them everywhere. " said the CDC．"The overall recommendation really is to avoid exposure. "
3 When that’s not possible, the guidelines say to consider wearing a simple surgical mask if you are in one of the three following situations. First, you’re healthy and can’t avoid going to a crowded place. Second, you’re sick and think you may have close contract with the healthy, such as a family member checking on you. Third, you live with someone who’s sick and thus might be in the early stages of infection, but still need to go out. Influenza pandemics can strike when the easy-to- mutate flu virus shifts to a strain that people never have experienced. Scientists cannot predict when the next pandemic will arrive, although concern is rising that the Asian bird flu might trigger one if it starts spreading easily from person to person.
4 During the flu pandemic, you should protect yourself. Avoid crowds, and avoid close con tract with the sick unless you must care for someone. Why can’t mask added to this self-protection list Because they help trap virus-laden droplets flying through the air with a cough or sneeze. Simple surgical masks only filter the larger droplets. Besides, the CDC is afraid masks may create a false sense of security. Perhaps someone who should have stayed home would don an ill-fitting mask and hop on the subway instead.
5 Nor does flu only spread through the air. Say someone covers a sneeze with his or her hand, then touches a doorknob or subway pole. If you touch that spot next and then put germy hands on your nose or mouth, you’ve been exposed. It’s harder to rub your nose while wearing a mask and so your face may get pretty sweaty under masks. You reach under to wipe that sweat, anal may transfer germs caught on the outside of the mask straight to the nose. These are the problems face masks may create for their users. Whether people should or should not use face masks still remains a question. The general public has to wait patiently for the results of the mask research scientists are still doing.
A．Reasons for Excluding Masks from the Self-protection List
B．Effort to Stop Flu Spreading
C．When to Use Face Masks
D．Guidelines on Mask Use
E. Warnings from the CDC
F. Danger of Infection through Germy Hands and MasksParagraph 5 ______.