根据下面句子的意思及所给的汉语提示，写出空缺处的单词或词组的正确形式。

1. If you are ___________ (粗心的), you'll fail the exam.

2. He looks very young, but he's ___________ (实际上) 55.

3. Can you guess how old my grandfather is? We have just celebrated his ___________ (第九十九个) birthday.

4. When I don't know a word, I often ___________ (查它) in the dictionary.

5. When he heard the cry for help, Danny quickly ___________ (穿衣) and ran out to the man.