Seldom ____ any mistakes during my past few years of working here. 

The bus hit against a tree in the fog and ______to the deep valley，with ten passengers killed and twenty wounded.

______________ about wild plants that they decided to make a trip to Madagascar for further research.

—I am really scared to know the scores of the test! —________，why did you come here to see our teacher?

Though _____ money, his parents managed to send him to university.