How to say I studied for 3 months (not continuous)
&quot;下个暑假我学了三个月汉语&quot; has two problems.
First, &quot;下个暑假&quot; is next summer, not last. If it's next summer, &quot;了&quot; , as a resultative verb suffix, should not be there, since the action cannot have been completed yet. The correct time is &quot;上个暑假&quot; or better still, &quot;去年夏天&quot;. since you never indicated that it's during the summer vacation, so I would simply say &quot;夏天&quot;, summer.
Second, &quot;我学了三个月汉语&quot; tells me you learned Chinese for three months. And most people would understand it to be a continuous three months, unless you specify that it's off and on, just like you would in an English sentence. I would add an adverb of manner &quot;斷續&quot; before the verb to indicate it is off and on.
去年夏天我斷續学了三个月汉语。
If you want to add an adverb of place, then it will come before the verb.
去年夏天我在上海斷續学了三个月汉语。