根据句意、首字母及所给汉语意思写出所缺单词
He looks sad.What’s the m___________ with him?
Can you (想像)what happened to the Malaysia airplane?
There’s something wrong with my _____________ (胃)
Don’t be _______________(担忧的) before the exam.
Can’t you see the _______(标志) “No smoking”?