すぐ知ったかぶりをするんだから。
tbd
The reason is they immediately pretend to know.
The reason is they are frankly know-it-alls.
The reason is they immediately wing it.
The reason is they immediately say things off the top of their heads.
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すぐ， 直ぐ
1. immediately, at once, right away, directly
2. soon, before long, shortly
3. easily, readily, without difficulty
4. right (near), nearby, just (handy)
5. honest, upright, frank, straightforward
立即，立刻
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を
1. indicates direct object of action
2. indicates subject of causative expression
3. indicates an area traversed
4. indicates time (period) over which action takes place
5. indicates point of departure or separation of action
6. indicates object of d...
表示动作的直接对象；表示经过的场所；表示离开或分开的点