1.worse
adjective
of poorer quality or lower standard; less good or desirable
(在质量、品德等方面)更坏的,更差的,更糟的
the accommodation was awful and the food was worse.
住宿条件很差,而伙食更糟.
2.down
用来养活那个生病的男孩的费用降到了20000
其实up也可以,意思是那个男孩的费用增加到20000,根据语境吧
3.a ,in
4.is joining