They look very much alike, but their characters are q________ different. Charlene Choi（蔡卓妍）, 19, one half of Hong Kong pop group Twins, is l________ and active. The older sister, Gillian Chung（钟欣桐）, 20, is quiet and gentle.

　　S________ they were discovered in 2000, they have had nine albums（专辑）including the latest hit Evolution（进化论）. Many of their albums have sold over 100,000 copies. Their songs often talk about friendship, love or life at school. Their songs are about their o________ stories and lives.

I ________ use a clock to wake me up because at six o’clock each morning the train comes by my house.

A. couldn’t??? B. mustn’t??????? C. shouldn’t???? D. needn’t