先改成一般疑问句再倒装,或举例也可以

所谓的倒装分为：完全倒装和部分倒装
而ONLY在句首引导的是部分倒装.
部分倒装,即把助动词提到主语之前.
下面我们来看你给的句子.
1、He is able to afford the money now.助动词是is
Only is he able to afford the money now
2、She often watches TV after she has finishes her chores and homework.助动词是does
Only does she often watch TV after she has finishes her chores and homework.
以此类推
3、助动词是did
4、助动词是did
再附几句例句：
Only in this way,can you learn English well.只有这样,你才能学好英语.
如果句子为主从复合句,则主句倒装,从句不倒装.例如：
Only when he is seriously ill does he ever stay in bed.病得狠重时,他才卧床休息.
楼主应该理解了吧?不理解再联系我~