Honored Contributori use cpld as combinational logic.the circuits don't need Oscillator.so if i don't connect a external Oscillator to cpld,can it work normally?
moreover,can internal oscillator be used as general clock?
Honored ContributorAs long as you do not use registers like a DFF, you do not need any clock.
But be aware that using pure combinatorial logic output could mean that there are glitches or spikes due to different combinatorial delays. I assume you talk about the MaxII device, then have a look at page 42 (http://www.altera.com/literature/hb/max2/max2_mii5v1.pdf) it should be possible to use the internal oscilator.
