Mary is _________ engineer. She works for ________ big company

1. Mary is _________ engineer. She works for ________ big company.

A. an / a ​B. a / a ​C. an / the​D. X / X

2. Peter plays __________ guitar very well. 

A. a​      B. an​C. the ​D. X

3. _________ January is __________ first month of the year.

A. the / X​B. X / X​C. the / the​D. X / the

4. Look outside! __________ sky is getting dark.

A. a​B. the​C. X ​D. an

5. We live in ___________ small house. It is ___________ most beautiful house.

A. a / the​B. the / a​C. an / the​ ​D. the / an