Editing Guide to technical writing (section)

===Passed or past?===
In English these two words are confusing because they are pronounced exactly the same, but the meaning is different and they can be used in similar contexts. "Passed" is the pass tense of the verb "pass," whereas "past" indicates going by.  So how do we check if we've made the right choice of word in our technical writing? Take these two examples:

* The voltage went past the maximum limit and the transistor overheated.

* The voltage passed the maximum limit and the transistor overheated.

The trick is to put them in the future tense (in your mind) and see what happens:

* The voltage will go past the maximum limit and the transistor will overheat.

* The voltage will pass the maximum limit and the transistor will overheat.

Notice that changing from past to future leaves the word "past" unchanged, but "passed" changes to "pass." This is how to tell if you got them the right way around.