〜ことがある koto ga aru
〜ことがある（koto ga aru）means “there are times when; sometimes do”. Attached to a present-tense plain verb (dictionary or ない form), it expresses that something happens occasionally — 'there are times when…'. Formation: V-る／V-ない＋ことがある（〜こともある）
there are times when; sometimes do
N4Formation
V-る／V-ない＋ことがある（〜こともある）
Explanation
Attached to a present-tense plain verb (dictionary or ない form), it expresses that something happens occasionally — 'there are times when…'. Note: this is different from V-た＋ことがある, which expresses past experience. The present form here is about recurring occasional events, not experience.
Examples
Note
Don't confuse with V-た＋ことがある (past experience: '(once) have done'). The variant こともある softens to 'it can also happen that…'.
FAQ
〜ことがある — what does it mean and how is it used?
there are times when; sometimes do. Attached to a present-tense plain verb (dictionary or ない form), it expresses that something happens occasionally — 'there are times when…'. Note: this is different from V-た＋ことがある, which expresses past experience. The present form here is about recurring occasional events, not experience.
〜ことがある — how do you form it?
V-る／V-ない＋ことがある（〜こともある）
〜ことがある — any usage notes?
Don't confuse with V-た＋ことがある (past experience: '(once) have done'). The variant こともある softens to 'it can also happen that…'.