Вставить правильный вариант.

1) he goes to work by train. ( -, the, a)
2) this is shop i told you about. ( the, a, -)
3) could you be so kind as to turn off light? ( a, the, -)
4) this is big shoe selling center. center is very popular with people. ( a \ the, the \ a, the \ an)
5) mosquitos are dangerous insects. ( -, the, a)
6) young people like walking in center of st. petersburg. (the, a, -)
7) if you take right turn you’ll get lost! ( a, -, the)