20. His sister left home in 1998, and______since.
28. In the coldest of the winter, trees stood with their bare branches(枝干)_________the sky.
27. Yang Liwei was picked from the 14 candidates for the Chinese space adventure and became China’s first astronaut _______ his great efforts.
26. Our school volleyball team has _____ their training to prepare for the coming match.
25. — Shirley won the first prize in the English speech contest. —Woo! ________ she has made since the beginning of this term!
24.The students were ____ over the ____ problem, listening to the teacher with a ____ expression on their faces.