You must _______ ________ in the corridor.
line up
You must ______ ______ in the school hall.
sit still
You mustn't ______.
spit
You mustn't ______ ______ __________.
pick the flowers
You mustn't ________.
litter
You must ______ _______ in the library
keep quiet
You must ________ _________ ________ ________.
keep off the grass