It's not something you can force, no, though it would be nice to have that as an option. There's an algorithm in place that chooses the content of the lessons for you, based on both your personal track record and what it knows about the general difficulty of the sentences.
While the algorithm gets a lot of things right, it has a tendency to favour the easier sentences quite heavily, which means that the most challenging sentences seldom get shown - as their overall fail rates understandably are higher.
oooh does the French people rip this sentence of from Norway (''Je suis plein'') to say that they are drunk? Funny stuff, in Québec (French canadian), we say ''Je suis chaud'' (litteraly ''I'm hot'' because of the heat alcohol produce in the throat) or ''je suis pacté'' (litteraly ''I'm pacted'' because you walk like you have tones of bags in your arms)