N3 Vocabulary · Test 84

うっかり means 'carelessly, inadvertently, absent-mindedly.' The sentence says: 'I overslept and rushed out of the house, so I carelessly forgot to close my room's window.' うっかり～するのを忘れてしまった is a natural pattern expressing an unintentional lapse caused by being in a hurry.

• 1やっと means 'finally, barely (with difficulty).' It implies achieving something after effort, which doesn't fit forgetting to close a window.
• 2ぐっすり means 'soundly, deeply (sleeping).' It is only used with sleep (ぐっすり眠る), not with forgetting something.
• 3そっと means 'quietly, gently, softly.' Rushing out of the house and 'quietly' forgetting to close a window is contradictory and unnatural.

• 寝坊ねぼうする — to oversleep
• 慌あわてて — in a panic, hastily
• うっかり — carelessly, inadvertently
• やっと — finally, barely (with difficulty)
• ぐっすり — soundly (sleeping deeply)
• そっと — quietly, gently, softly

内緒 (ないしょ) means 'secret, confidentiality.' The sentence means 'I didn't tell anyone about this matter and kept it secret all along.' 内緒にする / 内緒にしている (to keep something secret) is the standard expression, fitting perfectly with 誰にも言わずに (without telling anyone).

• 1裏側 (うらがわ) means 'the back side, the reverse side.' This is a physical spatial term and cannot be used as a verb phrase for keeping a secret.
• 3後方 (こうほう) means 'rear, behind.' This is a spatial/directional noun and does not fit the context of keeping a secret.
• 4中身 (なかみ) means 'contents, inside.' This refers to what is inside something (a box, a bag, etc.) and is unrelated to secrecy.

• 内緒ないしょ — secret, keeping something confidential
• 裏側うらがわ — back side, reverse side
• 後方こうほう — rear, behind
• 中身なかみ — contents, inside