Answer:

1.Have you also noticed that Chen is a little down today?

2. Baekhyun knew and anticipated that he have failed his Math exam.

3. Kyungsoo talked with Suho regarding on how to improve their song performance tomorrow.

4. Kai just realised that he forgot his houses key when he reached the bus stop.

5. Chanyeol began to teach Sehun guitar lessons since last week.

*you can change the names I used