1. My colleague demanded that I  ________________(return) the books I borrowed from him.

2. Although he ____________________(keep) on working hard£¬he didn't finish that task on time.

3. Having studied in Spain for four years£¬my sister Nancy   __________(acquire) a good knowledge of Spanish.

4. Most of his girlfriends failed to meet with his father's  __________(approve)£®

5. In the company he is senior  __________Tom£¬while in life he is Tom's junior__________two years.