More historical buildings in the old town will fall down ________we try our best to protect them.
—Where are the Greens? —They are in Guilin ________ vacation.
Don’t look out, please look ________ me.
The weather is very cold, but everyone ________ having a good time.
In summer, the weather in Jinan is ________ hot.
All the students are cleaning. ________ are cleaning the floor, and ________ are cleaning the desks.