例句：
It was incumbent on them to attend.
他们必须出席。
Our children attend the same school.
我们的`孩子上同一所学校。
There are plans to extend the no-smoking area.
现已有扩大无烟区的计划。
The meat is chemically treated to extend shelf life.
猪肉经过化学处理以延长保存期。
Careful maintenance can extend the life of your car.
精心保养可延长汽车寿命。
