Quote Originally Posted by unnamed View Post
Thanks all for replies. I do know that one can change the position of adverb in one sentence to modify its meaning, especially in negative tense. So, sometime in daily english speaking I feel hard to control the meaning of the sentence by modifying the adverb. Can someone suggest some easy ways for me to play with this problem?
Generally the adverb modifies the verb or verb phrase right next to it (in front or behind). So

“I do not understand completely” and “I do not completely understand” are equivalent in meaning in that “completely” modifies “understand”

“I completely do not understand” has a different meaning because “completely” now modifies the entire “do not understand” rather than just “understand”

There is no absolute rule, but one simple way to remember this is to place the adverb next to or as close to the verb that it modifies as possible, unless you want it to modify more than just the verb.