(2013·安徽师大附中高三七模)Don't use water to put out the fire if oil catches fire. As is known, oil ________ float on water.

 The chairman ________ hold office for five years according to the constitution.

—Where are Lucy and Lily?—Oh , the two girls must _______ a game in the garden now.

 No student ______ go out of the school campus after 10:00 at night without permission according to the school regulations.

 One of the rules is that every student ________ wear school uniform while at school.