The circular mirrors are effective in lighting fires , while the parabolic mirrors are not , although they may have been used to generate smoke . The circular mirrors are effective at lighting fires while the parabolic mirrors are not , although they may have been used to produce smoke .
Cermin pekeliling berkesan dalam menyalakan api, manakala cermin parabola tidak, walaupun mereka mungkin telah digunakan untuk menghasilkan asap. Cermin pekeliling berkesan dalam menyalakan api manakala cermin parabola tidak, walaupun mereka mungkin telah digunakan untuk menghasilkan asap.