Question

7. A picture _____________________ (sometimes print) on the front of T-shirts. Формула to be+3V

Answer 1

A picture is sometimes printed on the front of t-shirts

Answer 2

The sentence you provided is incomplete, but if you want to complete it using the formula "to be + 3rd form of the verb," you can say:

"A picture is sometimes printed on the front of T-shirts."

In this sentence, "is" is the form of the verb "to be," and "printed" is the 3rd form of the verb "print," which creates the passive voice construction.