These are good. I would suggest, however, that #3, #8 and #11 are much more equal in stress. If I had to assign stress, it would be (b) for #8 and (b) for #11.
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yolla3 . Don't forget to SHUT DOWN your computer before you go home.a or b, I'd say.
yolla8 . Pete is very fit because he WORKS OUT in the gym three times a week.b.
yolla11 . The thieves BROKE IN through the bedroom window.b.