根据句意，用括号内所给单词的适当形式填空。
It is ________ (fair) to make gentlemen pay for everything.Let’s go Dutch (AA制)！
Like e-mail and ATMs, some ________ (invent) make the speed of life faster than before.
The charity walk ________ (it) is very meaningful, to most teenagers, it’s not easy.
A map will be useful in the forest, especially if you get ________ (lose).