Line continuations are not used in C#, since an explicit line terminator (;
) is required.
If you're asking, in terms of style, whether it's a good idea to break a line into multiple lines, that's debatable. The StyleCop rules force a line to either be defined on a single line, or for every element to be on a separate line. I personally think this is a good guideline, and I usually choose to break a line completely into its parts if it's too long to fit into a good 80-90 character wide editor.
Edit in response to your new question:
In this case, I would follow the guidelines above. Personally, in your specific case, I'd leave this on one line:
SomeMethod(int someInt, Object someObject, String someString, bool someBool)
{
...
}
This is a nice, short moethod declaration, and I see no reason to split it. I'd only split it if the number of arguments, and the lengths of the types, became far to long for one line of text.
If you do split it, however, I'd split it into separate lines for each argument:
SomeMethod(
int someInt,
Object someObject,
String someString,
bool someBool)
{
...
}
This way, at least it's obvious how and why it's split, and a developer won't accidentally skip one argument since two are on a single line.