Although he knew little about the large amount of work done in the field , he succeeded ____other more well-informed experimenters failed.
19. --- Could you tell me how the sea sand comes about ? --- Sea waves dash against the rock. In this way , the sea sand ___ .
18. A new ___ bus service to Tianjin Airport started to operate two months ago .
17. Greatly moved by what he did , ____ .
16. My dear , where have you ___? I___ you everywhere .
15. We all greatly ___ your cooperation in the building of the power station .