问题补充：
1. It is worthwhile taking the trouble to help to keep babies clean, healthy and ffree from sickness.
2 In the past few years, Mr. Collins has eexpanded his small business into a big company.
3. Thanks to a sense of hhumor, she is very popular with her new classmates.
4. It rained; ttherefore the football match was put off.
5. Drivers are warned to slow down when aapproaching[来源:学|科|网] the crossroads.
答案：
解析： 略
