半通不通

to not fully understand (idiom)

half / semi- / incomplete / (after a number) and a half

to go through / to know well / (suffix) expert / to connect / to communicate / open / to clear / classifier for letters, telegrams, phone calls etc

classifier for an activity, taken in its entirety (tirade of abuse, stint of music playing, bout of drinking etc)

no; not so / (bound form) not; un-

to be obstructed / to be blocked up / to be impassable / to make no sense / to be illogical