Attached to a verb's dictionary form, ~ばかりだ means a situation keeps changing in one direction only — usually getting worse, with no sign of stopping. It stresses a one-way trend. (Note that ~ばかり in other patterns can also mean 'only/just' with nouns, but the ~ばかりだ trend usage is the key N3 point here.)
[Verb dictionary form] + ばかりだ
景気は悪くなるばかりだ。
Keiki wa waruku naru bakari da.
The economy just keeps getting worse.
悪くなる + ばかりだ shows a one-way downward trend
彼の病気はひどくなるばかりで、良くなる気配がない。
Kare no byouki wa hidoku naru bakari de, yoku naru kehai ga nai.
His illness only keeps worsening, with no sign of improvement.
ひどくなるばかり emphasizes continuous decline in one direction
円安が進み、物価は上がるばかりだ。
En'yasu ga susumi, bukka wa agaru bakari da.
With the weak yen, prices just keep rising.
上がるばかりだ marks an unstoppable one-way increase
• Uses the verb DICTIONARY form + ばかりだ for the 'one-way trend' meaning. • The trend is usually negative, but can be any single-direction change. • Different from ~たばかり (just did) and ~ばかり (only), which use other forms.
The JLPT rarely asks whether you recognise a pattern — it asks which of several similar patterns fits. These are the ones ~ばかりだ is tested against.
一方だ also means 'keeps changing one way' and is nearly synonymous; ~ばかりだ leans slightly more emotional/negative and colloquial.
~たばかり (past form + ばかり) means 'just finished doing'; ~ばかりだ (dictionary form) means 'keeps trending one way'.
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