Underlining or highlighting an iBook

When I underline an iBook in IOS7 on an iPad in red, or highlight in yellow, I find it hard to underline or highlight the specific line I want to mark. There's an unwanted magnifying glass that shows often a line or two lines above or below. How do you do that accurately? And without endless redoing?

Once you've done that with one line, how do you select, for example, the first few words of the next line, if that is what you want to underline or highlight?

Thanks.

If you have the same frustration with iOS 7's select & copy function, I finally bought an adonit 'Jot Pro' stylus.

It helped with the selection frustration for me with my iPad 2.