3.Put the verbs in brackets into the present continuous or the present simple a) Today, I(ride) my bike to school.
b)Kristen(make) a cake now?
c)I (play) tennis every week.​

a) Today, I am riding my bike to school.
Answer: In this sentence, the action "ride" is happening at the moment of speaking, so we use the present continuous tense. The correct form is "am riding."

b) Kristen is making a cake now?
Answer: In this sentence, the action "make" is happening at the moment of speaking, so we use the present continuous tense. The correct form is "is making."

c) I play tennis every week.
Answer: In this sentence, the action "play" is a regular or habitual action that occurs every week. For regular or habitual actions, we use the present simple tense. The correct form is "play."

To summarize:
a) Today, I am riding my bike to school. (Present continuous)
b) Kristen is making a cake now? (Present continuous)
c) I play tennis every week. (Present simple)