The local government announced that only when the fire was under control to return to the

网友回答

A. the residents would be allowed
B. had the residents been allowed
(答案→)C. would the residents be allowed
D. the residents had been allowed
解析：考查Only引导的部分倒装句。Only引导的倒装句要满足两个条件，only放在句首，且强调的是状语。本题only放在了后面句子的句首，强调是是时间状语从句when the fire was under control。故使用部分倒装的形式。句意：当地政府宣布，只有当大火被控制住以后，据居民们才可以返回家中。故C正确。