Can I put a 700 x 35 tire on a Cannondale Quick 2 that has a 700 x 28 tire?
Unfortunately manufacturers tend not to publish max tire sizes, and ties of nominally the same width can vary quite a bit in actual width.

Checking the Cannondale web site shows that the Quick 2 model comes with nominally 30mm tires as standard. You can probably go up to 32mm with no problems but there may not be clearance for 35mm.  

The place with the least tire clearance is typically between the chainstays. Measure the installed width of your 28mm tires and see of there is an additional 2.5 or 3.5 mm or clearance between the tires and frame.

You can also consider running a lower tire pressure on poor surfaces for better comfort and traction.