Mexicans wear face masks in the belief that the masks will protect them from the influenza A (H1N1) virus, formerly referred to as swine flu, in Mexico City in this combination photo.     眼下，H1N1甲型流感（即之前的猪流感）正在墨西哥肆虐。而墨西哥人的幽默感却没有因此而减少。在首都墨西哥城的街头，人们戴着各式各样的口罩，给紧张的气氛带来一丝轻松。