Here are the correct tense forms for the verbs in each sentence:

1. Wendy **comes** to my workshop every Sunday.
2. My mother and my sister **are preparing** dinner at the moment.
3. My grandmother **is buying** some fruits at the supermarket now.
4. My brother **plays** football twice a week.
5. Lan **has** Maths on Tuesdays, but she **has** Science on Tuesday this week.

If you need any further explanations or assistance, feel free to ask!