Suitable for joking on April Fool's Day.

Jokes suitable for April Fool's Day are as follows:

1. Stick a note at the entrance of the self-study building: Please do not study in this building for inspection. Please forgive me for any inconvenience.

There is a wooden board hanging on the water heater of the self-study building: it is broken and needs repairing.

3. Blackboard notice: Due to the maintenance of lines in this building, the lights will be turned off after 19: 00 at night.

4. Notice on the blackboard in the classroom: Teacher XXX can't attend class due to illness. Please study freely and tell yourself that you will have class today. So, get up early, carry your schoolbag and attend classes as usual.

5. Find someone who really wants to do it and take out his book. If possible, take them all out, coat them with 502 inside and double-sided tape outside, so that that person only needs to bring a book to school.