Could you please help me describe the pictures I posted you and check these sentences.
1) Go and fetch some chalk, will you?
Open the window halfway to let some fresh air in.
2) You should hand in your dissertation by next Monday.
Wipe off the blackboard.
3) If you enter the classroom ten minutes after your lesson starts, you won't be let in.
4) Your parents justify your absence by filling and signing the excuse slip.
Sure! I would be happy to help you describe the pictures and check the sentences. However, as a text-based AI, I am unable to directly view or analyze any pictures. Therefore, I can only provide assistance with textual information and answer questions based on that.
If you have any specific questions regarding the sentences you provided, please let me know and I will be glad to help you.