Ring nebulae are often found around massive stars such as Wolf-Rayet stars , OB and Of stars and Luminous Blue Variables ( LBVs ) .
In this paper we report on two ring nebulae around blue supergiants in the Large Magellanic Cloud .
The star Sk - 69 279 is classified as O9f and is surrounded by a closed shell with a diameter of 4.5 pc .
Our echelle observations show an expansion velocity of 14 km s ^ { -1 } and a high [ N ii ] \lambda 6583Å/H \alpha ratio .
This line ratio suggests nitrogen abundance enhancement consistent with those seen in ejectas from LBVs .
Thus the ring nebula around Sk - 69 279 is a circumstellar bubble .

The star Sk - 69 271 , a B2 supergiant , is surrounded by an H \alpha arc resembling an half shell .
Echelle observations show a large expanding shell with the arc being part of the approaching surface .
The expansion velocity is \sim 24 km s ^ { -1 } and the [ N ii ] \lambda 6583Å/H \alpha is not much higher than that of the background emission .
The lack of nitrogen abundance anomaly suggests that the expanding shell is an interstellar bubble with a dynamic age of 2 \times 10 ^ { 5 } yr .