Select the sentence with the correct use of a modal auxiliary:
a.
I must go to the park yesterday.
b.
She can playing the piano very well.
c.
You should wear a helmet while riding a bike.
d.
They must helping the teacher yesterday.
a.
I must go to the park yesterday.
b.
She can playing the piano very well.
c.
You should wear a helmet while riding a bike.
d.
They must helping the teacher yesterday.