謝謝牙仙一貫的的勤於動腦！！補課中有例句。

謝謝牙仙的一貫的勤於動腦！

補課中有例句：

(1) “have to, had better, used to”要用下列方式反問：

They used to smoke, didn't / usedn't they?

所以，你這句話可以是：

He used to be a sailor, didn't/usedn't he?