i notice that infantry vs vehicle attack range is 1.if a infantry attack a vehicle from a adjacent hex.should we count it as close-range attack or normal-range attack.thanks for answering

I have always played this as a close range attack even though the range is 1 (normal attack) it also satisfies the rules for a close range attack so 4, 5, 6 all hits

It is Close Range.

Close range. That is why tanks are vulnerable to infantry in built-up areas.

Its an exceltent rule actually.