the temperature will f__ below zero in the night this is a s__problem.we must solve it.there are at l__ three thousand students in our school

问题描述:

the temperature will f__ below zero in the night this is a s__problem.we must solve it.
there are at l__ three thousand students in our school

The temperature will ( fall ) below zero in the night this is a (serious)problem.There are at (least) three thousand students in our school.

fall,serious,least