As we all know the H1N1 Flu is so serious, students can’t go into the school _______ they take the temperature and get sure they don’t have a fever.

Samples of blood from Cholera infected patients have been sent to the blood center _______. [ ]

下列句子中，没有语病的一项是（ ）

ng doesn’t ________ mean you’re happySometimes, it just means that you’re strong enough to face problems

I have to go home. My parents do not allow me to ___________ too late.