运用括号里词的正确的时态完成填空，并说明理由
There's an ambulance at the house next door.I expect someone ____ (take)ill.

I expect someone must have taken ill.我想肯定有某人生病了。

expect除了表示“期待”的意思外，还有“预料”的意思。
must +have done表示一种对过去或现在完成动作的推测。如：
He must have finished his homework.他一定已经完成作业了。（对现在完成的动作的推测）
He must have reviewed his lesson yesterday ,for he answered the question excellently.他昨天肯定预习功课了，因为这个问题他回答得太好了。
顆餹兩種菋的疑问有道理。一般情况下是不能随便加情态动词的。
媛媛说书上提供的答案has been taken 是对的。I expect someone has been taken ill.我想/猜有人生病了。
be taken ill有生病的意思，但不常用。字典上可查到，仅此而已。