Here are the completed sentences:

45. It’s the rules to remove your shoes and belts when you go through the airport security checkpoint. → **You must remove your shoes and belts when you go through the airport security checkpoint.**

46. It’s not necessary for Laura to take part in the sports day if she doesn’t want to. → **Laura does not have to take part in the sports day if she doesn’t want to.**

47. Jack / pleased / because / he / get / A / biology test. → **Jack is pleased because he got an A in his biology test.**

48. Trains / be / most popular form / public transport / the United Kingdom. → **Trains are the most popular form of public transport in the United Kingdom.**

49. Riding / bike / fast / go / bus / in rush hours. → **Riding a bike is faster than going by bus in rush hours.**

50. Tommy / not have / as much / homework / his sister. → **Tommy does not have as much homework as his sister.**