（某人）必须做某事（去某处）

Be necessary (for one) to do something (go somewhere)

一旦你开始做某事，你就必须做到底。

I'd like to start by doing.

当你想表达必须做某事的意思时，使用这个词是完全可以被接受的。

When you want to express that something is obligatory then it is perfectly acceptable to employ it.