根据句意，用方框中所给单词的适当形式填空。（每小题1分，共5分）。

polite    work   write  speak  understand

 
Mr. Green spoke very loudly so that he could make himself___________ at the meeting.
There are many English ___________ in the world. They think speaking English is very popular.
Do you have any trouble _________ out this math problem .
Some people think it is__________ to ask someone’s age.
___________ English is not the same as oral English.