How to modify a two-character verb that has an object using 得?
'吃饭'， (eat rice= having meal) is a compound word verb, and it is also an intransitive verb (verb that doesn't take object). To illustrate the difference between [single character verb + noun] and [two characters verb + noun], I would change the example to '吃水饺' (吃 + 水饺)

[(吃水饺)- (吃得)- 很快]
[(保守机密) -(保守得)- 很嚴]

As you can see, you can modify '保守' with '得' the same way as '吃'
Although  &quot;保守机密保守得很嚴&quot; is technically correct in grammar, it is too wordy. Native speakers would do the following instead

Shorten a compound word verb to a single character, in the case of '保守', the shortened form is '守'. Your sentence would become &quot;守机密守得很嚴&quot;

In many cases, the object noun can also be shortened --&gt;&quot;守密守得很嚴&quot;

Only repeat the first character of the compound word verb. For example: &quot;攻击敵方陣地攻击很如火如荼&quot; --&gt; &quot;攻击敵方陣地攻很如火如荼&quot; (omit 击)

The best way is to use a simpler structure [(adv) + (verb) + (noun)] --&gt; [(如火如荼地)(攻击)(敵方陣地)]

For Intransitive Verbs (verb that cannot take noun), don't repeat the verb after 得 and directly go to the adverb

Example: 战斗 (to battle) is an 'intransitive verb'
Simply write &quot;战斗得很激烈&quot;
&quot;战斗战斗得很激烈&quot; . &quot;战斗战得很激烈&quot; or &quot;战斗斗得很激烈&quot; are all wrong
Another example: '伤风' (get a cold) is an 'intransitive verb'
Simply write &quot;伤风得很严重&quot;
&quot;伤风伤风伤得很严重&quot; or &quot;伤风伤得很严重&quot; is wrong