根据句子意思，用括号中所给单词的正确形式填空。(每空限填一个单词)
【小题1】The whole family are looking forward to Dad's_________________ (forty) birthday.
【小题2】In the UK, many houses were small but ____________  (attract), though rather old.
【小题3】____________  (probable) no one is free from mistakes, only some make more and some less.
【小题4】The boy has been ____________  (miss) for five days and there are fears for his safety.