How To Use Slack off In A Sentence

The ropes of the tent are too tight. Slack off a little!
Slack off your speed as you approach the corner.
One of the other writers is the same as me, so we formed an e-mail support group where we can give each other a hard time when we start to slack off. Why am I so honest? « Sven’s guide to…
As soon as you start to slack off, their satisfaction and motivation decreases.
As soon as you start to slack off, their satisfaction and motivation decreases.

The ropes of the tent are too tight. Slack off a little!
Railroads can boom, then bust, and then even be torn up; a frenzy of highway building can then follow, to slack off in its turn; copper wire can be laid for telephone service, then be replaced by fiber-optic cable (the latter often following railroad grades or highways!); a power distribution grid can be built at great expense, perhaps in turn to be "obsoleted" by cheap photovoltaics or fuel cells .... Who Do You Say I Am
Which of the tested ingredients, if any, caused the yeast to slack off, resulting in the unrisen bread?
Slack off your speed as you approach the corner.
Slack off those ropes there ; there's a storm coming!