20. In the end, we _____the village.

A. reached　 B. arrived in　 C. arrived　　 D got

19.____ they become dirty, the lakes are not able to clean themselves

A. Once　　　 B. since　　 C. As　　　 D Because

18.A car was riding ____a bus,____ sat a woman driver.

A. in front of, in front of which　　　　　 B. in front of, in the front of which

C. in the front of, in front of which　　　 D. in the front of, in the front of which