Spectral-line energy distribution (SLED) for several millimeter and submillimeter lines toward 30 Dor-10 (left), N159W (center), and Carina-N and -S (right). In the left and central panel, the solid lines represent the predictions for the ¹²CO and ¹³CO SLED from the excitation analysis presented in Sect. 4 for 30 Dor-10 and in Pineda et al. (2008) for N159W. The gray-dashed lines represent the ¹²CO and ¹³CO SLED predicted by the clumpy PDR model fits. The excitation analysis and PDR model predictions for the [C i] and [C ii] lines are represented by triangles and boxes, respectively. In the right panel we show the ¹²CO SLED for the Carina-N and Carina-S regions presented by Kramer et al. (2008) using the same clumpy PDR model as used in this paper. The physical conditions derived from the PDR model are similar for 30 Dor-10 and Carina-N as well as for N159W and Carina-S, but they have different metallicity (Carina Z = Z_⊙; LMC Z = 0.4Z_⊙).