Помогите 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)